Influence of residual impurity background on the nonradiative recombination processes in high purity InAsGaSb superlattice photodiodes

The influence of the impurity background on the recombination processes in type-II InAsGaSb superlattice photodiodes with a cutoff wavelength of approximately 4.8 μm was investigated by electroluminescence measurements. Using an iterative fitting procedure based on the dependence of the quantum efficiency of the electroluminescence on the injection current, the Auger and Shockley-Read-Hall lifetimes were determined for photodiodes with background concentration below 1015 cm-3. The authors determined in which range of the injection current Shockley-Read-Hall or Auger recombination is predominant. At T=300 K, the findings indicate that in high quality material with a low background concentration Auger effect becomes the prevalent mechanism even at low applied current.