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Fisika Modern 15 molecules andsolid_semiconductor
- 8. .:: Semiconductor, Insulators, Conductors ::. Both full and empty bands do not partake in electrical conduction. Full band All energy levels are occupied by electrons Empty band All energy levels are empty ( no electrons) 07/03/11 © 2010 Universitas Negeri Jakarta | www.unj.ac.id |
- 17. 3- Electromagnetic Radiation : h = 6.62 x 10 -34 J-s c = 3 x 10 8 m/s 1 eV=1.6x10 -19 J To promote electrons from VB to CB Silicon , the wavelength of the photons must 1.1 μ m or less Near infrared 07/03/11 © 2010 Universitas Negeri Jakarta | www.unj.ac.id |
- 23. 07/03/11 © 2010 Universitas Negeri Jakarta | www.unj.ac.id | The energy of the free e - is related to the k free e - mass , m 0 is the propogation constant The waves are standing waves The momentum is (1) (2) By means of equations (1) and (2) certain e - momenta are not allowed by the crystal. The velocity of the electron at these momentum values is zero. The energy of the free electron can be related to its momentum momentum k Energy E versus k diagram is a parabola. Energy is continuous with k, i,e, all energy (momentum) values are allowed. E versus k diagram or Energy versus momentum diagrams
- 31. -1 -2 0 2 3 1 4 GaAs Conduction band Valance band 0 Δ E=0.31 Eg [111] [100] k Energy (eV) -1 -2 0 2 3 1 4 Si Conduction band Valance band 0 Eg [111] [100] k Energy (eV) 07/03/11 © 2010 Universitas Negeri Jakarta | www.unj.ac.id |
- 32. -1 -2 0 2 3 1 4 GaAs Conduction band Valance band 0 Δ E=0.31 Eg [111] [100] k Energy (eV) Energy band structure of GaAs Band gap is the smallest energy separation between the valence and conduction band edges. The smallest energy difference occurs at the same momentum value Direct band gap semiconductor 07/03/11 © 2010 Universitas Negeri Jakarta | www.unj.ac.id |
- 34. E g k E E E direct transition 07/03/11 © 2010 Universitas Negeri Jakarta | www.unj.ac.id |
- 35. E g k E E direct transition 07/03/11 © 2010 Universitas Negeri Jakarta | www.unj.ac.id |
- 36. E g k E 07/03/11 © 2010 Universitas Negeri Jakarta | www.unj.ac.id |
- 37. E g indirect transition k E 07/03/11 © 2010 Universitas Negeri Jakarta | www.unj.ac.id |
- 38. E g indirect transition k E 07/03/11 © 2010 Universitas Negeri Jakarta | www.unj.ac.id |