MBE growth of room-temperature InAsSb mid-infrared detectors

Some key growth issues for InAsSb mid-infrared detectors are presented. We investigate the influence of growth temperature and Sb/As flux ratio on InA sSb alloy composition and on carrier lifetime. The Sb mole fraction in InAs 1-xSbx depends linearly on the Sb flux using either As-2 or As-4 (0.02 less than or equal to x less than or equal to 0.16). However, the Sb incorporat ion rate is significantly lower using As-2 flux. The carrier lifetime in th ick InAsSb layers closely lattice-matched to GaSb is measured by time-resol ved photoconductivity. The values obtained vary from 15 to 200 ns depending on growth conditions. The main result is that the carrier lifetime increas es as the growth temperature deer-eases and seems to be limited by Shockley -Read recombinations. Finally, an InAs0.91Sb0.09 p i-n photovoltaic detecto r is grown and operates at room temperature. A detectivity of 1.5 x 10(9) c m root Hz/W at 3.39 mum and 250 It is measured. We show that the quality of the active region material ensures a sufficiently low generation-recombina tion current. (C) 2001 Elsevier Science B.V. All rights reserved.