Abstract
The incorporation of Bi in GaSb1−xBix alloys grown by molecular beam epitaxy is investigated as a function of Bi flux at fixed growth temperature (275°C) and growth rate (1μmh−1). The Bi content is found to vary proportionally with Bi flux with Bi contents, as measured by Rutherford backscattering, in the range 0<x≤4.5%. The GaSbBi samples grown at the lowest Bi fluxes have smooth surfaces free of metallic droplets. The higher Bi flux samples have surface Bi droplets. The room temperature band gap of the GaSbBi epitaxial layers determined from optical absorption decreases linearly with increasing Bi content with a reduction of ~32meV/%Bi.
Highlights
The incorporation of a dilute amount of Bi in III–V arsenide semiconductors has shown great promise for optoelectronics device applications operating in the near- and mid-infrared ranges [1,2,3,4,5]
A detailed understanding of Bi incorporation in GaSb is required in order to determine the properties of GaSbBi alloys and to be able to develop GaNSbBi alloys lattice matched to GaSb substrates
The GaSb1 À xBix alloys grown by liquid phase epitaxy (LPE) showed the expected lattice dilation [11], whereas the initial films grown by molecular-beam epitaxy (MBE) exhibited lattice contraction with respect to GaSb [10]
Summary
The incorporation of a dilute amount of Bi in III–V arsenide semiconductors has shown great promise for optoelectronics device applications operating in the near- and mid-infrared ranges [1,2,3,4,5]. There are recent reports on controlled N incorporation and the band gap reduction in GaNxSb1 À x alloys [6,7]. Our first studies of growth temperature- and growth rate-dependent MBE of GaSbBi used a fixed Bi flux and achieved Bi incorporation of up to 9.6% with high substitutionality and generally metallic droplet-free surfaces [16,17]. The present work deals with the control of Bi content in GaSbBi alloys by varying the Bi flux, at fixed growth temperature and growth rate, and determination of the resulting band gap variation. Point of GaSb and a GaSb0:95Bi0:05 alloy to illustrate the Bi-induced band gap reduction based on previous reports [16,17].
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