Trap-assisted tunneling current and quantum efficiency loss in InGaAsSb short wavelength infrared photo detectors

Abstract

We report the trap-assisted tunneling current and quantum efficiency loss in short wavelength infrared In0.22Ga0.78As0.2Sb0.8 photo detectors. Combining experiment data with a current-voltage model, we found that the trap-assisted tunneling current was boosted by increasing Beryllium (Be) doping in active region at room temperature. However higher Be doping level imposes no negative impacts on quantum efficiency. Four traps with energy levels located at 49 meV, 60 meV, 155 meV and 199 meV below conduction band minimum in a In0.22Ga0.78As0.2Sb0.8 alloy are extracted from the fitting of I-V curves. Transparency measurement of an un-intentional doped In0.22Ga0.78As0.2Sb0.8 sample yields an absorption coefficient of 5191 cm-1 at 2.25 μm. Combining with the measured value of absorption coefficient, the quantum efficiency dependence on diode length of In0.22Ga0.78As0.2Sb0.8 photo detectors is presented. Finally, by fitting quantum efficiencies of In0.22Ga0.78As0.2Sb0.8 photo detectors, we obtained that the minority electrons diffusion length is larger than 4 μm and the minority holes diffusion length is 0.2 μm. Quantum efficiency loss occurs at top N region of In0.22Ga0.78As0.2Sb0.8 photo detectors due to a short holes diffusion length.

InGaAsSb for cut-off tuned SWIR detectors

“…It has a host of applications including fiber optics, 10 thermophotovoltaic cells, 11, 12 lasers, 13,14 infrared light-emitting diodes, 15,16 and infrared photodetectors. 1,17,18 In order to design and develop optimal structures, a firm knowledge basis of various material properties and device performance has to be established. Studies conducted thus far have been largely focused on higher alloy fractions 19,20 with little to no work done on dilute alloys.…”