OMVPE growth of metastable GaAsSb and GaInAsSb alloys using TBAs and TBDMSb

Abstract

Abstract Epitaxial layers of the metastable alloys GaAsSb and GaInAsSb have been grown by organometallic vapor phase epitaxy (OMVPE) using tertiarybutylarsine (TBAs) and tertiarybutyldimethylantimony (TBDMSb) with conventional group III sources. Layers with compositions well inside the miscibility gap were successfully obtained. The key parameters for obtaining these metastable alloys are the use of low V/III ratios (≤ 1) and low growth temperatures. The Sb distribution coefficients for GaAsSb are close to unity on both GaSb and InAs substrates when V/III ratios of approximately unity are used. The distribution coefficients of Sb for GaInAsSb on GaSb and InAs substrates are slightly higher than unity for lower V/III ratios. The quality of the surface morphology is degraded as the composition moves further into the region of solid immiscibility. The hole concentrations of undoped GaInAsSb layers on GaAs substrates grown using conditions identical to those used for the InAs substrates are approximately 1 × 10 17 cm −3 at room temperature. The concentrations of In and Sb in the GaInAsSb layers were 0.05–0.23 and 0.75–0.95, respectively, on GaSb substrates and 0.23–0.39 and 0.82–0.89, respectively, on InAs substrates. These compositions correspond to band gap energies of 0.4–0.7 eV. Low-temperature photoluminescence (PL) spectra were observed for GaInAsSb layers grown on GaSb and InAs substrates at wavelengths of approximately 1.9 and 2.0 μm with half-widths of 20 and 25.3 meV, respectively.