InGaAs/GaAsSb Type-II superlattice based photodiodes for short wave infrared detection

Short Wave Infra-Red (SWIR) photodetectors operating above the response cutoff of InGaAs- based detectors (1.7-2.5 mu m) are required for both defense and civil applications. Type II Super-Lattices (T2SL) were recently proposed For near- room temperature SWIR detection as a possible system enabling bandgap adjustment in the required range. The work presented here focuses on a T2SL with alternating nano layers of InGaAs and GaAsSb lattice-matched to an InP substrate. A near room temperature SWIR cutoff of 2.4 mu m was measured. Electrical junctions were realized using Zn diffusion p-doping process. We realized and studied both mesa- and selective diffusion- based p-i-n photodiodes. Dark currents of mesa based devices were 1.5 mA/cm(2) and 32 mu A/cm(2) at 300 and 230 K respectively. Dark currents were reduced to 1.2 mA/cm(2) and 12 mu A/cm(2) respectively by utilizing the selective diffusion process. The effect of operating voltage is discussed. At 300 K the quantum efficiency was up to 40% at 2.18 mu m in mesa devices. D* was 1.7 x 10(10) cm . root Hz/W at 2 mu m. (C) 2017 Elsevier B.V. All rights reserved.