Ultralow dark current p-type strained-layer InGaAs/InAlAs quantum well infrared photodetector with background limited performance for T≤100 K

Abstract

An ultralow dark current normal incidence p-type strained-layer In0.3Ga0.7Al/In0.52Al0.48As quantum well infrared photodetector (PSL-QWIP) grown on (100) semi-insulating InP substrate by molecular beam epitaxy technique for 8–12 μm infrared detection was demonstrated for the first time. This PSL-QWIP shows background limited performance (BLIP) for T≤100 K, which is the highest BLIP temperature ever reported for a QWIP. Due to a 1.5% lattice mismatch between the substrate and quantum well, a biaxial tensile strain was created in the In0.3Ga0.7As well layers. As a result, the light-hole state becomes the ground state for the free hole with small effective mass. The dramatic increase of optical absorption can be attributed to the large in-plane density of states and the small light-hole effective mass as a result of heavy- and light-hole state inversion. The dark current density and BLIP detectivity for this PSL-QWIP were found to be 7×10−8 A/cm2 and 5.9×1010 cm−√Hz/W, respectively, at λp=8.1 μm, Vb=2 V, and T=77 K.