Improvement of R 0A product of type-II InAs/GaSb superlattice MWIR/LWIR photodiodes

Abstract

The effects of atomic hydrogen and polyimide passivation on R 0A product of type-II InAs/GaSb superlattice photo detectors for cut-off wavelength of both 6.5 μm and 12 μm were investigated. Low temperature current–voltage measurement shows that the use of atomic hydrogen during molecular beam epitaxy growth can improve R 0A product by 260% for 6.5 μm cut-off superlattice diodes and by 50% for 12 μm cut-off ones. The R 0A product of polyimide-passivated diodes with 12 μm cut-off is about 80% higher than those un-passivated ones. Wannier–Stark oscillations at higher reverse bias were observed for polyimide-passivated superlattice diodes with 12 μm cut-off. No Wannier–Stark oscillations were observed for un-passivated superlattice diodes, indicating that surface leakage current dominates in un-passivated diodes, while intrinsic dark current mechanisms such as tunneling and diffusion current dominate in polyimide-passivated diodes.