1.8 Double Heterostructures

1.8 Explain how a double heterostructure works. Who are the Nobel prize winners for this invention?

A double heterostructure is a sandwich of one material between another material. It is a PIN junction, and the material of the intrinsic region of the PIN junction is a material with a smaller bandgap than the P and N regions. This structure…

  • Enables direct current injection via trapping of carriers
  • Light is generated in the intrinsic region where carriers are recombined.
  • Light is confined for a resonator feedback system as the intrinsic region layer serves as a waveguide.
  • It can be assumed that nearly all carriers recombine in the intrinsic region.

Nobel prize winners are (2000): Jack Kilby (1/2), Zhores Alferov (1/4), Herbert Kroemer (1/4)


Electronic Recombination/Generation Mechanisms (1.6, 1.7)

1.6. List and explain all the basic electronic recombination/generation mechanisms. Which one is required for lasers to operate?

  • Spontaneous Recombination
  • Stimulated Emission
  • Photon Absorption
  • Non-radiative Recombination

1.7 Describe the main ways of non-radiative recombination in semiconductor lasers/

Non-radiative recombination:

  • A conduction band electron and a valence band hole recombine without generating photons
  • Energy dissipated by heat or kinetic energy
  1. Non-radiative recombination by crystal defects, surfaces:
  • Electron and hold recombine but do not generate photon
  • Proportional to carrier density N
  • Caused by surface, point defect, interface, etc

2. Auger Recombination:

  • Energy from recombination is transferred to another electron or hole instead of photon generation
  • Proportional to carrier density N^3.
  • Energy from electron and hole is transferred to a third particle.