<title>Normal incidence p-type strained-layer In<formula><inf><roman>0.3</roman></inf></formula>Ga<formula><inf><roman>0.7</roman></inf></formula>As/In<formula><inf><roman>0.52</roman></inf></formula>Al<formula><inf><roman>0.48</roman></inf></formula>As quantum well infrared photodetector with background limited performance at 77 K</title>

Abstract

An ultra-low dark current normal incidence p-type strained-layer In<SUB>0.3</SUB>Ga<SUB>0.7</SUB>As/In<SUB>0.52</SUB>Al<SUB>0.48</SUB>As quantum well IR photodetector (PSL-QWIP) grown on semi-insulating (100) InP substrate by MBE technique has been demonstrated for the first time. This PSL-QWIP shows a background limited performance (BLIP) for T<EQ100 K, which is the highest BLIP temperature ever reported for the QWIPs. Due to a 1.5% lattice mismatch between the substrate and the quantum well, a biaxial tensile strain is created in the quantum well, which results in the inversion of the light-hole and heavy-hole ground state inside the quantum well. Since the light-hole state with large in-plane density of states becomes the ground state for the free holes with small effective mass, a large enhancement of the valence intersubband absorption occurs in this QWIP. The dark current density and the BLIP detectivity D<SUB>BLIP</SUB><SUP>*</SUP> for this PSL-QWIP were found to be 7 X 10<SUP>-8</SUP>A/cm<SUP>2</SUP> and 5.9 X 10<SUP>10</SUP> cm - (root)Hz/W, respectively, at (lambda) <SUB>p</SUB> equals 8.1 micrometers , V<SUB>b</SUB> equals -2V, and T equals 77 K.