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Theory of the P-N junction

Theory of the P-N junction. G eneration and Recombination. 4 .1 Semiconductor transport equations. Continuity equation. 4 .2 Generation & Recombination. T hermal Generation & Recombination. 4 .3 Transition Rates. 4 .3.1 fermi’s golden rule.

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Theory of the P-N junction

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  1. Theory of the P-N junction

  2. Generation and Recombination • 4.1 Semiconductor transport equations

  3. Continuity equation

  4. 4.2 Generation & Recombination • Thermal Generation & Recombination

  5. 4.3 Transition Rates • 4.3.1 fermi’s golden rule Matrix element coupling initial and final states

  6. Derivation of Fermi’s golden rule

  7. 4.3.2 optical processes in a two level system

  8. Steady state

  9. 4.4 photon generation

  10. 4.4.3 microscopic description of absorption • Dipole approximation

  11. Direct gap

  12. Indirect band gap

  13. 4.4.6 other types of behavior • Multiple step photon generation Absorptions by excitons and sensitisers

  14. 4.5 Recombination

  15. 4.5.2 Radiative recombination Derivation of the radiative recombination rate Intial state： Final state：

  16. By last session’s conclusion Substituting for

  17. Forapplication, interested in one direction, reduce to 1/4

  18. 4.5.3 simplified expressions for radiative recombination Carrier density independent and properties of the material

  19. Degenerate semiconductor Minority carrier radiative lifetime

  20. Larger for materials with a high absorption coefficient, and therefore radiative recombination is more important in direct bad gap materials. Relative to absorption, contributions from energy levels closer to the band edges are really important

  21. Radiative recombination from either band to impurity states inside the band gap can be very important, and can dominate over band-to band events. When =qV

  22. 4.3 bimolecular recombination

  23. MULTI-STEP PROCESS? • Relaships between rates and carrier densities?

  24. Three carrier –process :Auger recombination

  25. Lifetime for Auger recombination • In p-type material

  26. Momentum concervation

  27. Shockley Read Hall recombination

  28. Derivation of SRH recombination rate

  29. Surface and grain boundary Recombination

  30. Traps vs recombination centers

  31. Chapter 3 Electrons& Holes

  32. Quasi thermal equilibrium

  33. Current densities under bias

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