Dark current analysis of an InAs/GaSb type II superlattice infrared photodiode with SiO₂ passivation

Abstract

In this study, we present the current–voltage (I–V) characteristics of a 10 ML InAs/10 ML GaSb type-II superlattice (T2SL) with p-i-n structures for mid-infrared detection. At a negative bias and a temperature of 50 mV and 77 K, respectively, the cut-off wavelength of the fabricated T2SL photodiode with SiO₂ passivation on the mesa side wall was approximately 5.6 μm, and the dark current density was found to be 1.9 × 10^–5 A/cm². The bulk dark current model was adopted in this study to obtain the measured values by modeling, assuming the generation-recombination lifetime of the carrier to be approximately 60 ns, and considering the surface leakage current, as well as the four dark current mechanisms. At low operating temperatures, we inferred that the T2SL photodiode was limited by the effects of surface leakage, whereas the effects of the band-to-band and diffusion components of the dark current were negligible. Therefore, reducing the surface leakage current to obtain high-performance detectors requires the development of advanced passivation materials and technology.