Dark current mechanisms and spectral response of SiO2-passivated photodiodes based on InAs/GaSb superlattice

The electrical performance of SiO2 passivated type-II superlattice double heterostructure photodiodes is demonstrated. Compared to unpassivated samples, a dark current of 4.009 × 10− 5 A/cm2 and the corresponding differential resistance-area of 165.82 Ω·cm2 at zero bias voltage are achieved at 77 K. The temperature-dependence and bias-dependence of the dark current are studied experimentally. According to fitting results, the existence of the SiO2 passivated layer alters the band bending at the interface, which influence the generation-recombination and trap-assisted tunneling current and then it is presented that the total dark current is reduced by introducing the SiO2 passivation technology. At 77 K, the corresponding spectral responsivity and detectivity of the samples are measured at a bias voltage of − 50 mV and the 100 % cutoff wavelength is determined to be 10.6 μm, which is fitted well with the simulation results of temperature dependence of experimental data.