MBE growth of room-temperature InAsSb mid-infrared detectors

Abstract

Some key growth issues for InAsSb mid-infrared detectors are presented. We investigate the influence of growth temperature and Sb/As flux ratio on InAsSb alloy composition and on carrier lifetime. The Sb mole fraction in InAs 1− x Sb x depends linearly on the Sb flux using either As 2 or As 4 (0.02⩽ x⩽0.16). However, the Sb incorporation rate is significantly lower using As 2 flux. The carrier lifetime in thick InAsSb layers closely lattice-matched to GaSb is measured by time-resolved photoconductivity. The values obtained vary from 15 to 200 ns depending on growth conditions. The main result is that the carrier lifetime increases as the growth temperature decreases and seems to be limited by Shockley–Read recombinations. Finally, an InAs 0.91Sb 0.09 p–i–n photovoltaı̈c detector is grown and operates at room temperature. A detectivity of 4.5×10 9 cm Hz / W at 3.39 μm and 250 K is measured. We show that the quality of the active region material ensures a sufficiently low generation–recombination current.