Solid state lighting, GaN LEDs and lasers
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Gallium Nitride LEDs are on the way to replace light-bulbs and fluorescent tubes, and GaN lasers have many applications including Blue-Ray storage. This presentation introduces the basic technologies

Gallium Nitride LEDs are on the way to replace light-bulbs and fluorescent tubes, and GaN lasers have many applications including Blue-Ray storage. This presentation introduces the basic technologies

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Solid state lighting, GaN LEDs and lasers Presentation Transcript

  • 1. Solid state lighting August 18, 2008 This is a free trial version with a few sample pages only. Please download latest full version of the report here: http://www.eurotechnology.com/store/solidstatelighting/ Solid state lighting, GaN LEDs and lasers by Gerhard Fasol PhD Eurotechnology Japan K. K. www.eurotechnology.com Tokyo, August 18, 2008 (Version 11) ©1996-2008 Eurotechnology Japan K. K. All Rights Reserved ©1996-2008 Eurotechnology Japan K. K. 1 www.eurotechnology.com
  • 2. Solid state lighting August 18, 2008 About the Author of this report�   Gerhard Fasol is President and Chief Executive Officer of Eurotechnology Japan KK, a boutique consultancy firm for leaders that he founded in 1996 in Tokyo. Eurotechnology Japan KK advises several of the world’s largest blue-chip corporations, financial institutions, the Government of Finland and the European Union on strategy and mergers and acquisitions. Fasol has been working with Japan’s high-tech sector since 1984. He was manager of one of Hitachi’s research-and-development labs, and was Associate Professor of the NTT Telecommunications Chair at Tokyo University.   Regarding the field of this report, Fasol is the co-author, with key inventor Shuji Nakamura, of The blue laser diode: The complete story (2nd ed, Springer-Verlag, October 2000). As well, he has worked for about 12 years in compound-semiconductor research. He has briefed the President of Germany, Horst Koehler, and many other global leaders about Japan’s technology sector. In August 1995, Fasol briefed US Senator Jeff Bingaman about gallium-nitride light-emitting diodes. Senator Bingaman’s bill for energy-efficient lighting is mentioned in this report.   Fasol graduated with a PhD in Semiconductor Physics from Cambridge University and Trinity College, Cambridge ©1996-2008 Eurotechnology Japan K. K. 2 www.eurotechnology.com
  • 3. Solid state lighting August 18, 2008 Executive Summary�   The global lighting industry is about to change with the emergence of solid state lighting. This revolution is: ➔  motivated by the resulting energy savings and reduction of environmental impact ➔  Enabled by the invention of GaN and OLED technology ➔  And accelerated by politics and government (“Ban the Bulb” legislation)   Today’s size and impact of the lighting industry: ➔  US$100bn for lighting fixtures (of which US$30bn is for lamps). ➔  A total of 15bn installed screw-based light sockets (4bn in the US; 3.6bn in the EU). ➔  US$230bn for electricity + US$50bn for kerosene in the developing world. ➔  Energy-efficient lighting could save US$67bn (100 nuclear-power plants), 600m tonnes of CO2 emission or more and 10,000kg of mercury emission.   Ban the bulb - Politics accelerates move to energy-efficient lighting: ➔  The California Lighting Efficiency and Toxics Reduction Act (signed by Governor Arnold Schwarzenegger on 12 October 2007). ➔  Senator Jeff Bingaman: “Energy Efficient Lighting for a Brighter Tomorrow Act”. ➔  Well positioned companies (eg, Philips) push for energy-efficient lighting, GE closes its incandescent light-bulb factories.   Gallium-nitride LED-based solid-state lighting on the way to replace bulbs and tubes: ➔  Can cut the lighting electricity bill by 90%. ➔  LEDs have 50,000 hours lifetime compared to 1,000 hours for incandescent bulbs. ➔  Moore’s law for semiconductors: progress is faster-than-expected. ➔  GaN Light Emitting Diodes (LEDs) and lasers were developed by Shuji Nakamura at Nichia Chemical Industries (located in Anan, Tokushima-ken, Japan) based on InGaN/AlGaN. The first GaN light emitter was demonstrated by Jack Pankove in the 1970s, and Isamu Akasaki (Matsushita, Univ of Nagoya and Meijo Univ) developed many inventions which enabled Shuji Nakamura’s first commercialization. Largely invented in Japan, Asia-Pacific companies at important positions today in the GaN field. ©1996-2008 Eurotechnology Japan K. K. 4 www.eurotechnology.com
  • 4. Solid state lighting August 18, 2008 Agenda�   Executive Summary   The solid state lighting revolution ➔  Today’s lighting industry ➔  Energy consumption, efficiency and environmental impact ➔  Government action, legislation, “Ban the bulb” ➔  Developing countries   Physics and technology ➔  GaN devices: the three key steps for the breakthrough ➔  White LEDs ➔  Lasers ➔  Why did Shuji Nakamura at Nichia succeed where many much larger corporations failed?   Markets for GaN LEDs ➔  Traffic signals, street lights, displays and signage, architectural, automotive, backlights, general lighting   Markets for GaN Lasers   Patent issues and the “Club of Five”   The emerging new industry structure ➔  Nichia ➔  Frontline LED makers ➔  Equipment makers and supplies   Trends and projections   Summary ©1996-2008 Eurotechnology Japan K. K. 5 www.eurotechnology.com
  • 5. Solid state lighting August 18, 2008 The solid state lighting revolution ©1996-2008 Eurotechnology Japan K. K. 6 www.eurotechnology.com
  • 6. Solid state lighting August 18, 2008 The solid state lighting revolution is about to disrupt the global lighting industry What drives the solid state lighting revolution?�   Enabled by technology ➔  The solid state lighting revolution is only possible because of the discovery of GaN LEDs and OLEDs in the 1990s   Driven by economics and environmental considerations ➔  Today’s lighting (incandescent bulbs and fluorescent tubes) wastes energy, creates more greenhouse gases than necessary, and releases harmful poisons (mercury, lead) into the environment ➔  2 billion people have no electricity. They use kerosene for lighting, and they need to pay 5000 times more to get the same amount of light as they would pay would they use GaN LEDs   Accelerated by politics and government ➔  All major countries have legislation in place or on the way to enforce energy efficient lighting. It is very likely that incandescent light bulbs are gone within a few years ©1996-2008 Eurotechnology Japan K. K. 7 www.eurotechnology.com
  • 7. Solid state lighting August 18, 2008 Dramatic changes coming for today’s established lighting industry ©1996-2008 Eurotechnology Japan K. K. 10 www.eurotechnology.com
  • 8. Solid state lighting August 18, 2008 General Lighting “Ban the bulb” Political and Government actions ©1996-2008 Eurotechnology Japan K. K. 20 www.eurotechnology.com
  • 9. Solid state lighting August 18, 2008 Developing countries: the poorest get the worst deal today ©1996-2008 Eurotechnology Japan K. K. 24 www.eurotechnology.com
  • 10. Solid state lighting August 18, 2008 Physics and Technology ©1996-2008 Eurotechnology Japan K. K. 26 www.eurotechnology.com
  • 11. Solid state lighting August 18, 2008 Why are blue and white GaN LEDs important?�   Some years ago the active elements in radios and TV-sets were vacuum tubes. Many years ago these vacuum tubes have been replaced first by discrete transistors and now by integrated circuits (ICs).   Still today, the lighting industry is dominated by glass bulbs and glass tubes (fluorescent tubes), which despite gradual improvements are essentially a 100 year old technology with many disadvantages (short lifetime, bulky and breakable, difficult to recycle, causing environmental damage, inefficient: most energy input is converted into heat not desired light, etc)   GaN based blue, green, white LEDs for the first time allow to replace light bulbs and fluorescent tubes with semiconductors   GaN LEDs have started to replace light bulbs and fluorescent tubes starting with high-value applications (e.g. traffic lights, specialty lighting, medical applications) ©1996-2008 Eurotechnology Japan K. K. 27 www.eurotechnology.com
  • 12. Solid state lighting August 18, 2008 Why are blue lasers important?�  Blue (violet) GaN based semiconductor lasers allow to store information with approx. 4 times higher density and therefore are the basis for the next generation DVDs  Blue (violet) GaN based lasers have many other applications in medicine, printing, copying machines and other areas ©1996-2008 Eurotechnology Japan K. K. 28 www.eurotechnology.com
  • 13. Solid state lighting August 18, 2008 Who invented GaN blue LEDs and lasers? Three people:�   Jacques (Jack) Pankove (1970s at RCA Laboratories, now at the University of Colorado and Astralux Inc.) found that Gallium Nitride (GaN) can emit blue light. Jack Pankove’s memories of his early work can be found here: ➔  http://nsr.mij.mrs.org/2/19/text.html#section1   Professor Isamu Akasaki (1980s & 1990s initially at Matsushita Electrical Industries, then at Nagoya University and now at Meijo University) in patient and systematic research work in cooperation with Hiroshi Amano and others over many years developed methods to deposit device quality GaN films, developed and demonstrated p-type and n-type doping and developed GaN based light emitting diodes   Shuji Nakamura (1990s at Nichia Chemical Industries, and now at University of Santa Barbara) invented a long list of technologies and processes necessary for commercial application, and developed GaN LEDs and Lasers to the point of commercial products. His most important discovery is the “two-flow MOCVD process” to grow GaN films. ©1996-2008 Eurotechnology Japan K. K. 29 www.eurotechnology.com
  • 14. Solid state lighting August 18, 2008 Light spectrum of an LED, a light bulb and a laser�   Light bulb: tungsten filament heated to about 3000 C emits “black body” radiation over a broad spectrum. Most emission is invisible infrared heat radition. The efficiency is low, because most input energy is converted into heat, not into light.   LED: Light is emitted by the transition of electrons between energy levels, and therefore within a relatively narrow range of wavelenghts   Laser: the emission of a laser is determined by the resonance of an “optical amplifier” and an optical cavity. The light emitted is coherent (this means that the light waves are continuous without break in phase over a considerable range in time and space). Lasers can emit light in a very narrow beam in a very narrow wave length spectrum ©1996–2000 Eurotechnology Japan K. K. Blackbody radiation Laser of a light bulb http://www.eurotechnology.com/ LED Ultra-Violet Infrared 500 1000 1500nm wavelength ©1996-2008 Eurotechnology Japan K. K. 30 www.eurotechnology.com
  • 15. Solid state lighting August 18, 2008 Blue lasers for optical storage (Bluray)�   Diffraction limits the size of a focused laser beam to a spot with a width of the order of the wavelength of the light used, therefore the wavelengths limits the density of data storage: shorter wavelengths (blue, violet, UV) enable higher storage density   In principle, an optical near-field microprobe allows a much higher density of optical storage, however access is VERY slow using current knowledge Schematic of information storage on CD-ROM Diffraction spots of and magneto-optical disc red, green, blue and violet lasers 1 0 0 0 0 0 1 0 1 1 1 1 ©1995–2000 Eurotechnology Japan K. K. 800nm 500nm 450nm 400nm http://www.eurotechnology.com/ ©1996-2008 Eurotechnology Japan K. K. 31 www.eurotechnology.com
  • 16. Solid state lighting August 18, 2008 What is a blue light emi ing diode (LED)�   A light-emitting semiconductor diode (LED) or a laser   A light emitting diode (LED) consists of a stack of n- diode (LD) both consist of a stack of extremely thin type (left hand side) and a stack of p-type (right hand and precisely grown semiconductor layers of different side) material, forming a “p-n junction”. Electrons (red) materials and holes (green) follow the potential gradient of an applied voltage and recombine in the region of the p-n junction. The photons of the emitted light have an energy similar to the value of the energy gap. ©1995–2000 Eurotechnology Japan K. K. Electron energy p-GaN(Mg) 0.5µm electrons p-Al 0.15 Ga0.85 N (Mg) 0.15µm n-In0.06 Ga0.94 N (Mg,Zn) http://www.eurotechnology.com/ 0.05µm n-Al 0.15 Ga0.85 N (Si) 0.15µm donors blue emission 4µm n-GaN (Si) Zn acceptors GaN Buffer Layer 0.03µm holes after: Nakamura, IEEE Circuits and Devices (1995) Sapphire Substrate ©1996-2008 Eurotechnology Japan K. K. 32 www.eurotechnology.com
  • 17. Solid state lighting August 18, 2008 What is a laser diode (LD)?�   LASER = Light Amplification by Stimulate Emission of Radiation ➔  Every laser consists of a light amplifier (which amplifies light by stimulated emission) combined with an optical resonant cavity: Laser = Light Amplifier + Resonant Cavity ➔  In most semiconductor lasers, the light amplifier and the resonant cavity are grown in the same structure, are strongly interlinked and some components may be shared.   Light Amplifier: a light amplifier increases the intensity of light in a certain wavelength range, when it is pumped above a threshold. Above this threshold, “stimulated emission” occurs. A light amplifier can be “pumped” electrically, optically, or by other methods. In the case of a semiconductor laser diode, pumping is optically in the first stages of research, however for devices pumping is almost always electrically ➔  In a semiconductor Laser Diode (LD) the light amplifier consists of a structure similar to a light emitting diode (LED) with a pn-junction. However, the requirements for accuracy of design, accuracy of growth, purity, freedom from impurities and crystal defects are much more stringent that for LEDs.   Resonant Optical Cavity: an optical cavity has certain resonant frequencies. When the amplification spectrum of a light amplifier within a resonant cavity coincides with the resonant frequencies of the optical cavity lasing can occur. ➔  The resonant cavity of a semiconductor laser can in the simplest case consist of the cleaved (broken) edges of the semiconductor, or in more sophisticated cases of multi-layer dielectric mirrors. ➔  A resonant cavity has “eigen-modes” or resonant modes, the transmission spectrum, the reflection spectrum, spontaneous noise spectrum of a well-formed resonant cavity shows narrow peaks� ©1996-2008 Eurotechnology Japan K. K. 33 www.eurotechnology.com
  • 18. Solid state lighting August 18, 2008 Surface emi ing lasers (VCSELs) vs. Edge emi ing lasers�   Conventional edge emitting semiconductor lasers: the light emission is through the cleaved edge of the laser. Conventional edge emitting lasers are normally handled one-by-one are almost impossible to integrate in large numbers.   Surface emitting laser (Vertical Cavity Surface Emitting Laser = VCSEL). VCSELs are usually much smaller, can be integrated in large numbers on a substrate wafer, and are much easier to test one-by-one while still on the wafer ©1995–2000 Eurotechnology Japan K. K. http://www.eurotechnology.com/ Growth Direction internal or external reflectors to form resonant cavity Reflector Reflector active layer (amplifier) Surface emitting laser conventional (VCSEL) semiconductor laser ©1996-2008 Eurotechnology Japan K. K. 34 www.eurotechnology.com
  • 19. Solid state lighting August 18, 2008 What is a light amplifier?�   When light is emitted in an electronic transmission, two types of emission are possible: ➔  Spontaneous emission: in the case of a laser, spontaneous emission gives rise to “phase noise” and is not usually desirable. Methods to suppress spontaneous emission in lasers are desirable and have been proposed by researchers. In a laser spontaneous emission is necessary to start laser action, before the lasing threshold is crossed ➔  Stimulated emission: stimulated emission is the emission of photons stimulated (in resonance) with the electric field of other photons present in the amplifier. Stimulated emission occurs at sufficiently high intensities, an usually “population inversion” is necessary, the upper electronic level of the transition is stronger populated than the lower level. Therefore optical or electronic pumping is necessary to achieve stimulated emission   Light entering the amplifier is amplified by resonant emission, if the amplifier is pumped sufficiently for stimulated emission to occur and to overcome the losses due to absorption and scattering ©1996-2008 Eurotechnology Japan K. K. 35 www.eurotechnology.com
  • 20. Solid state lighting August 18, 2008 What is a resonant cavity?�   In optics a resonant cavity is usually called a “Fabry-Perot Cavity”, or “Fabry-Perot Resonator”   In the simplest case, a resonant optical cavity consists of two highly reflective flat mirrors which are very accurately parallel. Actually,   An optical resonant cavity has resonant modes, I.e. the transmission spectrum, the reflectance spectrum, noise spectrum etc. show very sharp resonances. The higher the quality and the better the design of the cavity, the sharper these resonances are.   In a VCSEL (vertical cavity semiconductor laser the resonant cavity is formed by stacks of layers grown on top of the substrate. The axis of the optical cavity, and laser emission is perpendicular to the substrate.   In a traditional edge emitting semiconductor laser the cavity is formed by the cleaved edges of the laser chip, usually the cleaved edge have to be coated by evaporating thin layers of dielectric material.   In semiconductor lasers, the optical amplifier and the resonant cavity are tightly integrated, strongly interact and influence each other: e.g. during laser operation the electron density in the structure changes, which changes the refractive index, and both the amplifier and the resonant cavity become inter-dependent. Therefore in a semiconductor laser, amplifier and resonant cavity must be designed together, not independently as is sometimes possible in large gas lasers. ©1996-2008 Eurotechnology Japan K. K. 36 www.eurotechnology.com
  • 21. Solid state lighting August 18, 2008 Why Gallium Nitride (AlGaN/InGaN)?� ©1996–2000 Eurotechnology Japan K. K.   AlN, GaN, InN materials all have a http://www.eurotechnology.com/ direct bandgap direct band gap, i.e. the optical 6.0 AlN indirect bandgap transitions across the bandgap are Energy Gap (eV) “allowed” and therefore much 5.0 MgS stronger than in the case of indirect bandgaps (which have “forbidden” 4.0 transitions), as in the case of Silicon ZnS MgSe Carbide (SiC). GaN 3.0   Before Nichia brought GaN blue LEDs AlP ZnSe on the market, commercial blue LEDs SiC AlAs 2.0 GaP used SiC, which are much less efficient InN due to the indirect bandgap GaAs CdSe 1.0 InP   Before Shuji Nakamura commercialized Sapphire after: Nakamura, IEEE Circuits GaN blue LEDs it was generally and Devices (1995) thought that II-VI compounds were 3.0 4.0 5.0 6.0 the path to blue LEDs and Lasers however defects in these materials Lattice Constant (Å) could not be controlled sufficiently and the life-time of the devices was too short ©1996-2008 Eurotechnology Japan K. K. 37 www.eurotechnology.com
  • 22. Solid state lighting August 18, 2008 The Three Key Steps To GaN Devices ©1996-2008 Eurotechnology Japan K. K. 38 www.eurotechnology.com
  • 23. Solid state lighting August 18, 2008 Three key steps had to be solved�  Lattice mismatch ➔  GaN is grown on Sapphire, which has a 15% smaller lattice constant than GaN, and different thermal expansion, leading to a very high defect density and cracking of the layers when the structures are cooled down after growth ➔  Akasaki solved this problem by developing AlN buffer layers ➔  Nakamura grew GaAlN buffer layers  High growth temperature ➔  thermal convection inhibits growth ➔  Nakamura solved this problem with his two-flow growth reactor (this invention by Shuji Nakamura is at the core of the US$ 600 million law suits before the Courts of Japan between Shuji Nakamura and Nichia Chemical Industries)  p-doping was impossible ➔  A semiconductor laser, semiconductor light emitting diode, transistor structures and other device structures require pn-junctions, I.e. junctions between p-type and n-type materials. Previous to Akasaki’s work p-type doping of GaN was impossibly ➔  Akasaki demonstrated p-type material which was e-beam annealed ➔  Nakamura found that annealing in Ammonia gas passivated the acceptors and solved this problem ©1996-2008 Eurotechnology Japan K. K. 39 www.eurotechnology.com
  • 24. Solid state lighting August 18, 2008 1. La ice mismatch�   Choice of substrate ➔  Silicon Carbide (SiC): good lattice matching, very expensive, patent issues ➔  Sapphire: used at present for most devices ➔  Ideally: GaN. However, GaN substrate wafers have not been available. Once they become available, it is expected that GaN devices grown on GaN will have much better properties than devices grown on Sapphire with high lattice mismatch   Sapphire as substrate ➔  15% difference in lattice constants between Sapphire and GaN and very large difference in thermal expansion initially made growth of devices impossible. ➔  Akasaki solved this issue by designing and growing a AlN buffer layer (Akasaki US- Patent 4855249, Applied Physics Letters) ➔  Nakamura grew GaAlN buffer layers (Nakamura US-Patent 5290393, Japanese Journal of Applied Physics)   Note that CREE generally uses SiC (Silicon Carbide) substrates to grow GaN devices.   It would be ideal to grow on GaN substrates, however these are not yet available in commercial quantities at this date. ©1996-2008 Eurotechnology Japan K. K. 40 www.eurotechnology.com
  • 25. Solid state lighting August 18, 2008 1. La ice mismatch�   Problem: large lattice mismatch and large difference in thermal expansion between Sapphire substrate and GaN/AlN   Solution: AlN Buffer layer (Akasaki, US-Patent 4855249, Applied Physics Letters   Solution: GaAlN Buffer layer (Nakamura, US-Patent 5290393, Japanese Journal of Applied Physics)   Ideal solution for the future: GaN substrates (still need to be developed, recent progress looks promising) GaN sound zone dislocation GaN semi-sound zone (150nm) lateral growth faulted zone (50nm) coalescence buffer layer (GaN or AlN) (50nm) Sapphire (α-Al2O3) ©1996–2000 Eurotechnology Japan K. K. http://www.eurotechnology.com/ after: Akasaki (APL, 1986) ©1996-2008 Eurotechnology Japan K. K. 41 www.eurotechnology.com
  • 26. Solid state lighting August 18, 2008 3. p-type doping: anneal in Nitrogen� ©1996–2000 Eurotechnology Japan K. K. http://www.eurotechnology.com/   Problem: Pankove (1971 at RCA Laboratories) 6 10 reported metal-insulator-semiconductor Gallium- Nitride light emitting diodes, but found p-type 5 doping to be impossible 10 Anneal in NH3: Resistivity (Wcm) (NH3 dissociates–   Proof of p-type doping: Akasaki (1988 at Nagoya 4 resulting atomic University) found that samples after Low Energy 10 Electron Beam Irradiation treatment (LEEBI) hydrogen, showed p-type conductivity. Thus Akasaki 3 passivates 10 demonstrated that in principle p-type doping of acceptors) GaN compounds was possible 2 10   Solution: Nakamura (1992 at Nichia, US-Patent 5306662) found the solution to the puzzle of p- 1 type doping (see image on left hand side): 10 ➔  Nakamura found that previous investigators had annealed the Anneal in N2 samples in Ammonia (NH3) atmosphere at high temperatures. Ammonia dissociates above 400 Celsius, producing atomic 0 10 hydrogen. Atomic hydrogen passivates acceptors, so that p- type characteristics are not observed. Nakamura (J.J.Appl.Phys. 1992) ➔  Nakamura solved this problem by annealing the samples in Nitrogen gas, instead of Ammonia 0 200 400 600 800 1000 Temperature (C) ©1996-2008 Eurotechnology Japan K. K. 43 www.eurotechnology.com
  • 27. Solid state lighting August 18, 2008 Some remaining technology issues�  Although commercial GaN devices are routinely produced today, several materials issues still remain and are under intensive research investigation: ➔  GaN substrate: at the moment GaN devices are mainly grown on Sapphire substrates, since GaN wafers of sufficient size and quality are not available. It is expected that growth on GaN wafers will lead to much lower defect densities, because the lattice constant mismatch will be much smaller ➔  High defect density: it is very puzzling that commercial GaN devices and particularly lasers operate with defect densities which are dramatically higher than in comparable GaAs or Silicon devices. This fact is not understood at the moment. It is expected that understanding this fact will lead to improvements to device quality. ©1996-2008 Eurotechnology Japan K. K. 44 www.eurotechnology.com
  • 28. Solid state lighting August 18, 2008 White GaN based LEDs ©1996-2008 Eurotechnology Japan K. K. 45 www.eurotechnology.com
  • 29. Solid state lighting August 18, 2008 GaN based LEDs cover a wide range of colors�   Using different material compositions and different phosphor compositions a wide range of colors can be produced with LEDs.   Using red/green/blue combinations a wide range of color compositions can be produced ©1996-2008 Eurotechnology Japan K. K. 50 www.eurotechnology.com
  • 30. Solid state lighting August 18, 2008 Long-Lifetime GaN Lasers ©1996-2008 Eurotechnology Japan K. K. 51 www.eurotechnology.com
  • 31. Solid state lighting August 18, 2008 Development of long-lifetime GaN lasers�   Lasers are much more difficult to develop than LEDs, and in the case of GaAs-based red and infrared lasers it took many years for the development of commercial semiconductor lasers.   The research path in semiconductor laser development is first to develop lasers which only work at very low temperatures (liquid Nitrogen temperatures) and under optically pulsed conditions. The development work leads: ➔  from optical pumping to electrical pumping ➔  from low temperature to room temperature ➔  from pulsed pumping to continuous pumping ➔  from short life-time to long life-time   Some of the most difficult issues to solve is high-defect density, and defect migration under the high currents of laser operation   Nakamura applied Epitaxially Laterally OverGrown (ELOG) GaN substrates to control defect density for laser structures � ©1996-2008 Eurotechnology Japan K. K. 52 www.eurotechnology.com
  • 32. Solid state lighting August 18, 2008 Schematic structure of Nakamura’s blue laser�   Shuji Nakamura (1997) used ELOG (epitaxially laterally overgrown) GaN substrates to control defects: seed windows in a SiO2 array control the defects   ELOG was one of the keys for Nakamura to succeed growth of lasers with 10,000 hours lifetime 4µm p-GaN:Mg (0.05µm) Al0.14Ga0.86N/p-GaN:Mg MD-SLS (120 x 25Å/25Å) p-GaN:Mg (0.1µm) p-Al0.2Ga0.8N:Mg (0.02µm) p-electrode n-In0.15Ga0.85N:Si/n-In0.02Ga0.98N:Si MQW (4 x 35Å/105Å) SiO2 n-GaN:Si (0.1µm) Al0.14Ga0.86N/n-GaN:Si MD-SLS (120 x 25Å/25Å) n-electrode n-In0.1Ga0.9N:Si (0.1µm) n-GaN:Si (3µm) cracks and voids seed-window SiO2 - mask (4µm) ©1997–2000 Eurotechnology Japan K. K. http://www.eurotechnology.com/ ©1996-2008 Eurotechnology Japan K. K. 53 www.eurotechnology.com
  • 33. Solid state lighting August 18, 2008 Schematics of ELOG for defect control�   Nakamura used the specifics of defect propagation on ELOG substrates to fabricate laser structures in low-defect areas of the structure InGaN-Laser structure p-electrode n-electrode n-GaN (3µm) ©2000 Eurotechnology Japan K. K. http://www.eurotechnology.com/ cracks and voids threading dislocations GaN (20µm) ELOG- substrate SiO2 (1µm) GaN (2µm) GaN buffer layer (30nm) 10 µm (0001) sapphire substrate ©1996-2008 Eurotechnology Japan K. K. 54 www.eurotechnology.com
  • 34. Solid state lighting August 18, 2008 Why Did Shuji Nakamura At Nichia Succeed Where Many MUCH larger Corporations Failed? ©1996-2008 Eurotechnology Japan K. K. 55 www.eurotechnology.com
  • 35. Solid state lighting August 18, 2008 Why did Shuji Nakamura at Nichia succeed where many MUCH larger multinationals and famous Universities failed?�   A quick direct answer is, that all other labs (with the exception of Akasaki in Nagoya) looked at II-VI compounds (ZnSe/ZnS) - and had given up working on Gallium-Nitrides because they thought it was hopeless. Work on ZnSe/ZnS did not succeed because II-VI compounds have low stability and are grown at low temperatures. Only Professor Akasaki (at Nagoya University and later at Meijo University) continued systematic work on GaN over many years.   Nichia’s Chairman and Founder (Nobuo Ogawa) gave Shuji Nakamura + 2 Assistants YEN 300 Million (approx. US$ 3 Million) to “gamble” on Gallium Nitride. This was about 1.5% of annual sales for Nichia. In addition, Nakamura had to learn MOCVD growth. For this purpose Nichia sent Nakamura for one year to the University of Florida to learn MOCVD in Professor Ramaswamy’s laboratory.   Large corporations tend to avoid risks more, and tend to take a more conservative approach to research - even in fundamental research (“jumping on the band-wagon” phenomenon)   Large corporations and research institutes tend to spend less research budget per researcher on average, e.g. NTT and other corporations spend on the order of US$ 250,000 to US$ 400,000 per researcher per year on average, so that it is very seldom that US$ 3 million + 1 year training in the US is available for the gamble on a new fundamental research project, which has not yet shown any proven results ©1996-2008 Eurotechnology Japan K. K. 56 www.eurotechnology.com
  • 36. Solid state lighting August 18, 2008 Management structure for Shuji Nakamura’s work�   Typical cooperative research   Shuji Nakamura’s research management structure of large environment during the most projects important phase of his work © 1998–2000 Eurotechnology Japan K. K. http://www.eurotechnology.com/ Diagram of a Typical Research Consortium Project Evaluation Committee Diagram of Nichia's Government Agency Industrial Technology Council Hierarchy for the subsidy and GaN-Blue Laser © 1998–2000 Eurotechnology Japan K. K. http://www.eurotechnology.com/ Designated R&D investment Program Government research funding Agency Research Researchers Government- dispatched Government Government Research Joint Research Industry joint from 30 Institutes Research Institute Agreement research laboratory private Director enterprises Several Government Research transfer General Chairman Chairman N. Ogawa Laboratories Scientists Equal partnership Research Research Center Group Joint Research with Center participation from industry Project Leader Deputy Project Leader Research scientists Group Leader Research scientists dispatched/invited Research Scientist dispatched/adopted Shuji Nakamura Domestic and overseas academia and research organizations ©1996-2008 Eurotechnology Japan K. K. 57 www.eurotechnology.com
  • 37. Solid state lighting August 18, 2008 The Nichia – Shuji Nakamura court case�   As widely reported in the press internationally there has been a number of court cases between Shuji Nakamura and Nichia concerning the patents covering Shuji Nakamura’s research work while he was still at Nichia (he has since moved to the University of Santa Barbara)   To our knowledge, the present status is, that the judgments have confirmed Nichia’s ownership of the key patent which Shuji Nakamura claimed to own   To our knowledge, the Tokyo District Court has decided that Shuji Nakamura deserves a 50% share of profits of his invention, and the Court estimated Nichia’s profits to be on the order of US$ 1.2 billion, so that Shuji Nakamura would deserve US$ 600 million in reward for his invention. Since Shuji Nakamura claimed US$ 200 million the court granted his demand in full.   The court case was taken by Nichia to a higher court, and a court supervised settlement between Nichia and Shuji Nakamura was reached, where Nichia agreed to Shuji Nakamura approximately US$ 8 million reward for his inventions – a dramatically smaller sum than initially awarded by the Tokyo District Court.� ©1996-2008 Eurotechnology Japan K. K. 58 www.eurotechnology.com
  • 38. Solid state lighting August 18, 2008 Markets for LEDs ©1996-2008 Eurotechnology Japan K. K. 59 www.eurotechnology.com
  • 39. Solid state lighting August 18, 2008 Main applications sectors for white and blue GaN LEDs�   Traffic signals and other specialty applications   Automotive head lamps   Backlighting for liquid crystal displays (LCD) ➔  Mobile phones ➔  Laptop computers ➔  Desktop computers ➔  TVs   Signage and out-door displays   General lighting ➔  Industrial ➔  Street lighting ➔  Households   Other applications ©1996-2008 Eurotechnology Japan K. K. 60 www.eurotechnology.com
  • 40. Solid state lighting August 18, 2008 Markets For GaN LEDs Tra ic Signals and Other Specialty Lighting ©1996-2008 Eurotechnology Japan K. K. 61 www.eurotechnology.com
  • 41. Solid state lighting August 18, 2008 LEDs for tra ic signals�   Traffic signals together with large area out- door flat panel displays where the first applications of GaN LEDs. The reasons are the initially high price of LEDs   LEDs are much more suitable for traffic lights than light-bulbs and in the near future it is expected that all traffic lights will operate with LEDs. The main reasons are: ➔  much lower energy consumption ➔  long lifetime (10 years and longer) ➔  better light quality (no filters)   Trend: at the moment most traffic light designs use a very large number of LEDs. In the future it is expected that traffic lights will be developed to include a much smaller number of LEDs reducing cost and energy consumption ©1996-2008 Eurotechnology Japan K. K. 62 www.eurotechnology.com
  • 42. Solid state lighting August 18, 2008 Markets For GaN LEDs Street lights ©1996-2008 Eurotechnology Japan K. K. 63 www.eurotechnology.com
  • 43. Solid state lighting August 18, 2008 Markets For GaN LEDs Displays and signage ©1996-2008 Eurotechnology Japan K. K. 65 www.eurotechnology.com
  • 44. Solid state lighting August 18, 2008 LEDs are starting to replace fluorescent tubes in outdoor signage�   LEDs are starting to appear in applications where fluorescent tubes would have been used in the past in outdoor signage and advertising applications.   LEDs consume less energy, live much longer, don’t show flicker when aging, can be controlled to show images, messages and movies, change color, and have far more flexibility� ©1996-2008 Eurotechnology Japan K. K. 69 www.eurotechnology.com
  • 45. Solid state lighting August 18, 2008 Markets For GaN LEDs Architectural lighting Interior design, shops… ©1996-2008 Eurotechnology Japan K. K. 70 www.eurotechnology.com
  • 46. Solid state lighting August 18, 2008 Markets For GaN LEDs Automotive lighting and headlamps ©1996-2008 Eurotechnology Japan K. K. 73 www.eurotechnology.com
  • 47. Solid state lighting August 18, 2008 LEDs for automotive lighting�   All lighting for cars including headlights and fog lamps will be soon replaceable by LED lamps   At recent Tokyo Motorshows most leading automotive electrical makers showed LEDs for car lighting applications based on red, yellow and white GaN based light emitting diodes   In the future semiconductor LEDs will enable “intelligent” lighting, e.g. lighting where the color composition corresponds to the external lighting conditions and other built-in intelligence and control which is impossible for traditional incandescent lamps ©1996-2008 Eurotechnology Japan K. K. 74 www.eurotechnology.com
  • 48. Solid state lighting August 18, 2008 Markets For GaN LEDs Mobile phones ©1996-2008 Eurotechnology Japan K. K. 77 www.eurotechnology.com
  • 49. Solid state lighting August 18, 2008 Markets For GaN LEDs Backlights for laptops, PCs and TVs ©1996-2008 Eurotechnology Japan K. K. 79 www.eurotechnology.com
  • 50. Solid state lighting August 18, 2008 Markets For GaN LEDs (D) General Lighting ©1996-2008 Eurotechnology Japan K. K. 81 www.eurotechnology.com
  • 51. Solid state lighting August 18, 2008 Markets For GaN Lasers ©1996-2008 Eurotechnology Japan K. K. 86 www.eurotechnology.com
  • 52. Solid state lighting August 18, 2008 Markets for GaN lasers�   The main application for GaN is for data storage and music storage. Due to the shorter wavelength, violet and UV GaN lasers allow a much higher data density.   The next generation DVD standards use blue GaN lasers with a wavelength of 405nm for reading and writing data. Two competing standards competed for prominence, however Blue-Ray won the race: ➔  Blu-Ray: promoted by SONY and the Blu-Disc Founders consortium of 11 consumer electronics companies plus Hewlett-Packard and Dell ➔  HD-DVD (Advanced Optical Disc) promoted by NEC and Toshiba (lost the race…)   Many other applications exist and are about to be developed, e.g. in the medical area ©1996-2008 Eurotechnology Japan K. K. 87 www.eurotechnology.com
  • 53. Solid state lighting August 18, 2008 Blu-Ray vs. HD-DVD and vs. DVD Parameter Blu-Ray HD-DVD DVD Recording Capacity 27 GByte 20 GByte 4.7 GByte Single layer (2 hours of HDTV, 13 hours of standard TV) Recording Capacity 54 GByte 32 GByte 9.4 GByte Dual layer Laser wavelength 405nm 405 nm 650 nm Numerical Aperture 0.85 0.65 0.60 Protection layer 0.1mm 0.6 mm 0.6 mm Data transfer rate 36Mbps 36 Mbps 11.08 Mbps Video Compression MPEG-2 MPEG-2, H.264 MPEG-2 Comments Blu-Ray Founders Toshiba, NEC DVD-Forum (promoted by SONY) ©1996-2008 Eurotechnology Japan K. K. 88 www.eurotechnology.com
  • 54. Solid state lighting August 18, 2008 Patent Issues ©1996-2008 Eurotechnology Japan K. K. 89 www.eurotechnology.com
  • 55. Solid state lighting August 18, 2008 Emerging new lighting industry structure ©1996-2008 Eurotechnology Japan K. K. 95 www.eurotechnology.com
  • 56. Solid state lighting August 18, 2008 Nichia ©1996-2008 Eurotechnology Japan K. K. 99 www.eurotechnology.com
  • 57. Solid state lighting August 18, 2008 Investor perspective: The Front line - LED makers ©1996-2008 Eurotechnology Japan K. K. 105 www.eurotechnology.com
  • 58. Solid state lighting August 18, 2008 Investor perspective: Equipment makers and other supplies ©1996-2008 Eurotechnology Japan K. K. 108 www.eurotechnology.com
  • 59. Solid state lighting August 18, 2008 Trends and projections ©1996-2008 Eurotechnology Japan K. K. 110 www.eurotechnology.com
  • 60. Solid state lighting August 18, 2008 Summary ©1996-2008 Eurotechnology Japan K. K. 112 www.eurotechnology.com
  • 61. Solid state lighting August 18, 2008 Summary�   Today’s global lighting industry amounts to approximately US$380bn annually for lighting fixtures, lamps, electricity and kerosene fuel (in the third world). Energy consumption, and environmental impact due to CO2 emission and release of poisons can be much reduced by replacing traditional light bulbs and fluorescent tubes with GaN based LEDs.   Legislation, environmental groups, and well positioned companies push for energy- efficient lighting solutions and reduction of toxic emissions. Incandescent bulbs are on the way out (“Ban the bulb” movement).   Japanese researchers at Nichia and Toyoda Gosei in the 1990s invented gallium- nitride (GaN)-based light-emitting diodes (LEDs), which made it possible for the first time to replace light bulbs and fluorescent tubes, starting the solid-state lighting revolution.   Moore’s law brings semiconductor-innovation cycles to the lighting industry.   GaN-based LEDs revolutionize the lighting industry, change industry structure and business models, break established market positions and allow newcomers (Nichia, Toyoda Gosei, Seoul Semiconductors) to enter the mainstream lighting industry.   From the investor perspective, in addition to the front-line LED manufacturers, luminaire makers, manufacturing equipment makers, and materials makers are also very important, as well as the impact on incumbents. ©1996-2008 Eurotechnology Japan K. K. 113 www.eurotechnology.com
  • 62. Solid state lighting August 18, 2008 References (1)�   Shuji Nakamura, Gerhard Fasol, Stephen J Pearton “The Blue Laser Diode: The Complete Story” ISBN 3540665056, Springer-Verlag, (Second Edition, September 2000)   Gerhard Fasol: quot;Room-Temperature Blue Gallium Nitride Laser Diodequot; SCIENCE, 272, p. 1751-1752 (21 June 1996)   Gerhard Fasol: quot;Fast, Cheap and Very Brightquot; SCIENCE, 275, p. 941-942 (14 Feb 1997)   Gerhard Fasol: quot;Longer Live for the Blue Laserquot; SCIENCE, 278, p. 1902-1903 (12 Dec 1997) ©1996-2008 Eurotechnology Japan K. K. 114 www.eurotechnology.com
  • 63. Solid state lighting August 18, 2008 References (2)�   Roland Haitz et al, “The case for a national research program on semiconductor lighting” (White paper presented at the 1999 Optoelectronics Industry Development Association in Washington, DC, on 6 October 1999)   Evan Mills, “The US$230 Billion Global Lighting Energy Bill” (manuscript dated June 2002, and Proceedings of the 5th International Conference on Energy-Efficient Lighting, May 2002, Nice, France) ©1996-2008 Eurotechnology Japan K. K. 115 www.eurotechnology.com
  • 64. Solid state lighting August 18, 2008 Glossary ©1996-2008 Eurotechnology Japan K. K. 116 www.eurotechnology.com
  • 65. Solid state lighting August 18, 2008 Glossary- Light emi ing diodes (LED)�   At the core of a light-emitting diode (LED) is a p-n junction - a junction of a p-type-doped and an n-type-doped semiconductor. When a voltage is applied to the LED, electrons are injected into the n-type side of the LED, and holes into the p-type side. The injected electrons and holes recombine at the location of the p-n junction and emit light. The photon energy (wavelength) of the light corresponds to the bandgap of the semiconductor material from which the LED is manufactured. Practical red and infra-red LEDs were invented by Nick Holonyak in 1962 at the R&D labs of General Electric (GE). (The first LED was made in 1907 by H.J. Round, who was assistant to Guglielmo Marconi at Marconi Company in the UK, however these first LEDs were not practically used.) Until Shuji Nakamura’s invention and commercialisation of blue LEDs, essentially only red and infra- red LEDs were commercially available for meaningful applications (weaker blue LEDs were available before Nakamura’s invention, but their light was too weak and the lifetime too short for common applications).� ©1996-2008 Eurotechnology Japan K. K. 117 www.eurotechnology.com
  • 66. Solid state lighting August 18, 2008 Glossary- Compact fluorescent lamp (CFL)�   Compact fluorescent lamps (CFL) are essentially small versions of the common fluorescent tubes. CFLs use about one-fifth to one- quarter of the energy of incandescent-light bulbs for a given light output. Therefore, about 70-80% of the electricity used for lighting could be saved by replacing incandescent lamps with CFLs. Although CFLs are substantially more expensive than incandescent lamps to buy, they have a much longer life.   The CFL was invented by Edward Hammer at General Electric in 1976. General Electric did not manufacture CFLs at that time. However, other companies began making and selling them from 1995. Hammer was awarded the IEEE Edison Medal 2002 for inventing the CFL.   CFLs contain mercury. In the US, the National Electrical Manufacturers Association is committed to limiting the amount of mercury used in CFLs. If broken, CFLs are a health hazard because of evaporating mercury. When CFLs are disposed of in landfills, they are likely to be crushed, enabling the mercury to escape into the atmosphere. Proper recycling is necessary to avoid this mercury load on the environment. ©1996-2008 Eurotechnology Japan K. K. 118 www.eurotechnology.com
  • 67. Solid state lighting August 18, 2008 Glossary�   General lighting service (GLS) ➔  GLS are lamps for general lighting   Luminaire (lighting fixture) ➔  The lighting industry uses the term luminaire (lighting fixture) to describe devices used to create artificial light. A complete luminaire may include some or all of the following components: light source (lamp); reflector to direct the light; aperture; lens; housing or shell; protective covers; electric ballast (if required, such as for fluorescent tubes); electronic driver circuitry (as for LED lamps); and wires or connectors to link the luminaire to a power source.   Luminous efficacy (luminous efficiency) ➔  The energy efficiency of light sources is the amount of light produced divided by the electricity consumed and is measured in lumens per Watt (lm/W).   Gallium Nitride (GaN) ➔  Gallium nitride is a III-V semiconductor crystal with a direct bandgap.   Solid-state lighting ➔  The light emitters for solid-state lighting (SSL) are solid-state devices, usually gallium-nitride (GaN) light- emitting diodes (LED) or organic light-emitting diodes (OLEDs).   Organic light-emitting diodes (OLEDs) ➔  Organic light-emitting diodes have applications in lighting and for flatpanel displays. The first OLED-based commercial flatpanel displays were introduced for mobile phones in Japan about 2006, and Sony introduced the first commercial, stand-alone OLED flatpanel display in the autumn of 2007. Development is also progressing on lighting applications of OLEDs.   MOCVD ➔  Metal organic chemical vapor epitaxy is a common crystal-growth method used to develop and manufacture GaN semiconductor light-emitting diodes and lasers. MOCVD allows the growth of device layers with single-atom-layer precision. ©1996-2008 Eurotechnology Japan K. K. 119 www.eurotechnology.com
  • 68. Solid state lighting August 18, 2008 More information:  Blogs: ➔ http://fasol.com/blog/ ➔ http://eurotechnology.com/blog/  Reports: ➔ http://www.eurotechnology.com/store/ ©1996-2008 Eurotechnology Japan K. K. 121 www.eurotechnology.com
  • 69. Solid state lighting August 18, 2008 Contact   Eurotechnology Japan KK   Shinagawa Intercity Tower A 28F   2-15-1 Konan, Minato-ku   Tokyo 108-6028, Japan   Tel +81-3-6717-4160   FAX +81-3-6717-4141 and +81-3-5477-7044   http://www.eurotechnology.com/   CEO: Gerhard Fasol PHD   Fasol@eurotechnology.com   Mobile: +81-90-8594-6291 ©1996-2008 Eurotechnology Japan K. K. 122 www.eurotechnology.com