Performance comparison between the InAs-based and GaSb-based type-II superlattice photodiodes for long wavelength...

In this paper, we report on the characterization of InAs/GaAsSb type-II superlattice long wavelength infrared photodiodes grown on InAs substrates by molecular-beam epitaxy and also present the device performance comparison with the superlattice devices grown on GaSb substrates. These devices with PIN structures had a 100% cutoff wavelength of 10 μm. The dark current density of InAs-based device at -30 mV reverse bias was 4.01 × 10^-4 A/cm² and the resistance-area product at zero bias (R₀A) was 36.9 Ωcm². The dark current density of GaSb-based device is higher more than one order of magnitude than that of InAs-based device. The temperature-dependence and bias-dependence of the dark current are studied experimentally and correlated to the theory. Good agreement was achieved between the measured I-V curves and the simulated ones, and between the experimental and theoretically predicted differential resistance values. Compared with InAs-based superlattice device, the generation-recombination current of GaSb-based device is larger and dominates in a wider temperature range due to shorter carrier lifetime and higher defect density.