Improvement of R0A product of type-II InAs/GaSb superlattice MWIR/LWIR photodiodes

The effects of atomic hydrogen and polyimide passivation on R(0)A product of type-H InAs/GaSb superlattice photo detectors for cut-off wavelength of both 6.5 mu m and 12 mu m were investigated. Low temperature current-voltage measurement shows that the use of atomic hydrogen during molecular beam epitaxy growth can improve RoA product by 260% for 6.5 mu m cut-off superlattice diodes and by 50% for 12 mu m cut-off ones. The ROA product of polyimide-passivated diodes with 12 mu m 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 pm 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. (C) 2009 Elsevier B.V. All rights reserved.