Investigation of trap-assisted tunneling current in InAs/(GaIn)Sb superlattice long-wavelength photodiodes

Trap centers with an energy level positioned 1/3 of the band gap below the effective conduction band edge are observed in the electroluminescence spectra of InAs/(GaIn)Sb superlattice photodiodes with a cutoff wavelength of 11 μm. The trap centers are recognized by simulating the low-temperature current–voltage characteristics of the diodes. Excellent quantitative agreement on both, the I–V characteristic and the differential resistance between the experimental data and the theoretical prediction is achieved. The quantitative simulation of the I–V characteristics shows, that the 77 K performance of InAs/(GaIn)Sb photodiodes is dominated by generation-recombination processes even at long wavelengths. Above 50 K, tunneling currents are not of importance.