SIC- A NEW ERA INPOWERELECTRONICSPrepared By:Krunal P. Siddhapathak (10bec097)
OUTLINE Introduction Why used in high temperature application? Advantages Applications Why SiC is not used? Conclusion
INTRODUCTION Silicon Carbide (SiC) is a very hard semiconductor material SiC has been used in abrasive products such as grindingwheels for more than one hundred years. Today, high quality monocrystal SiC substrates withdiameters up to 100 mm are commercially available and theirmain application is light-emitting diodes. SiC is becoming more widely used in power applicationssuch as power factor control in power supplies. SiC has a wide band gap of 3.2 eV which is almost three timesthe band gap of Si (1.1 eV). This quality enables semiconductor devices made out of thismaterial to maintain a satisfactory function even at highertemperatures.
INTRODUCTION(CONTD.) Silicon Carbide’s wide band gap makes it possible to producepower transistors that block high voltages and have low seriesresistance, leading to low conduction losses. Thanks to the low conduction losses, the chip size canbe reduced and it is possible to switch the transistors with lowswitching losses. The high band gap also enables power transistors to switchhigh voltage and current at high temperatures. In conclusion, SiCs power transistors are electricallyrobust, with excellent short circuit capabilities.
WHY SIC IS USED IN HIGHTEMPERATURE APPLICATIONS? The variation in current gainversus temperature is shownin figure As shown in figure there isonly 10 to 15% change incurrent gain whentemperature changes from300K to 400K. While normal transistor failat elevated temperature dueto significance increase incurrent gain.
ADVANTAGES Higher Power Density Through higher switching frequency at same or lowerlosses, enabling the use of smaller inductors, heat-sink andcapacitors Increase output power while maintaining system formfactor Lower System Cost Through lower losses and higher power density, smallercooling and increased power output for the same hardware Offer productivity improvement.
ADVANTAGES(CONTD.) Key SiC Features Wide band gap (3.2 eV, 3x Si) High break down field (2.4 MV/cm, 10x Si) High thermal conductivity (4 W/cm K, 3x Si) High temperature stability. Fast Switching Approximately 20 ns for turn-on and turn-off. Switching behaviour is not temperature dependant. No current tailing for SiC BJT.
ADVANTAGES(CONTD.) Robust and Reliable Normally OFF device. Highest rated operating temperature =175 C Positive temperature coefficient (Ron) No Secondary breakdown for SiC BJT Low leakage current. Short circuit resistance. No SiO2 gate oxide reliability issue.
APPLICATIONS High Efficiency Applications such as renewableenergy, industrial systems and mobile power all require highefficiency, small size and light weight. Fairchild is developing a series of device solutions that willoffer the industry’s highest efficiency compared to any othertransistors available today. These components also eliminate many of the size, weight andtemperature trade-offs associated with efficiency gains insilicon devices. High Temperature The ability for power semiconductors toprovide reliable operation at high temperatures.
APPLICATIONS(CONTD.) Lower Losses, Faster Switching, Higher PowerDensity Solar inverters Welding systems Mobile power DC-DC converters DC-AC inverters PFC input stages Motor drives
APPLICATIONS(CONTD.) Higher Operating Temperatures High temp DC converters High temp actuator controls High temp motor drivers Motor and turbine controls Surveillance
WHY SILICON CARBIDE DEVICESARE NOT AVAILABLE? Lack of suitable substrate for the industrial scalefabrication of power semiconductor devices. SiC can not be melted under controllable conditions It changes its state directly from solid to gaseous.
CONCLUSION Silicon carbide transistors has several advantages over silicontransistor like fast switching, high power reliability, hightemperature stability etc. Main disadvantages is that lack of substrate in fabrication ofpower semiconductor devices.
REFERENCES B.J.Baliga, “The Future of Power Semiconductor DeviceTechnology”, Proceedings of the IEEE, June2001,Vol.89, No.6, pp.822-832 Orellana Alavaro, Piepenbreier Bernhard, “Fast Gate Drivefor SiC-JFET using a Conventional Driver for MOSFETs andAdditional Protections,” The 30th annual Conference of theIEEE Industrial Electronics Society, pp. 938-943.