InGaAs/GaAsSb type-II quantum well photodetectors with quantum wells barrier layer for reducing dark current

We fabricated extended SWIR photodetectors with cutoff wavelength of 2.3.m by using lattice-matched InGaAs/GaAsSb type-II quantum wells as an absorption layer. The 100-pair InGaAs/GaAsSb quantum wells and InGaAs as a cap layer were grown on an n-type InP substrate by molecular-beam epitaxy. The p-n junction was formed by selective zinc diffusion using rapid thermal annealing. For dark current reduction, photodetector with a barrier layer between the absorbing layer and the cap layer was also fabricated. In each device, in addition to absorption in the InGaAs cap layer, absorption which is possibly originating from the quantum well layer was observed in a wavelength range from 1.6 mu m to 2.3 mu m. By comparing dark current of each device, dark current reduction by the barrier layer was also confirmed.