Effect of Sb pre-deposition on the compositional profiles in MOVPE-grown InAsSb/InAs(111) multi-quantum wells

This paper describes the effect of Sb pre-deposition on the composition mod ulation in InAsSb/InAs strained-layer multi-quantum wells. The multi-quantu m-well structures, grown by metal-organic vapor-phase epitaxy (MOVPE) on In As (1 1 1) substrates, had periods of approximate to 20 nm and nominal InAs 0.8Sb0.2 layer thicknesses of approximate to 4.5 nm. Sb surface coverages f rom 0 to 1.4 monolayers (ML) were deposited on the InAs surfaces during gro wth interruptions prior to alloy layer growth. With no pre-deposition, kine matical simulations of measured theta-2 theta X-ray diffraction (XRD) patte rns yielded best fits for exponential composition profiles as expected for Sb segregation. The lie Sb segregation lengths were 1.2-1.6 nm. When approx imate to 0.8 ML of Sb was pre-deposited, XRD simulations indicated sharper InAsSb-on-InAs interfaces. Sb coverages of greater than or equal to 1 ML br oadened the XRD superlattice reflections, indicating that interface roughne ss increased. (C) 2000 Published by Elsevier Science B.V. All rights reserv ed.