State-of-the-art AlGaAs alloys by antimony doping

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Abstract
Historically GaAlAs alloys grown by molecular-beam epitaxy have high deep level concentrations (>1016 cm−3), low luminescent efficiency with broad peaks, and are difficult to dope controllably below mid 1016 cm−3. We report the effect that the low incident antimony molecule fluxes during growth appear to help reduce the density of deep levels below 1014 cm−3, which then allows reproducible doping control in the low 1015 cm−3 range. Exciton-dominated photoluminescence with half widths ∼4.0 meV are now routinely achieved using this technique. Further evidence for the quality improvement of AlGaAs by heavy atom (Sb) doping comes from high 4 K two-dimensional electron gas mobilities for low sheet electron densities, e.g., 1.3×106 cm2/V s for n=2×1011 cm−2. SIMS profiles of antimony content are presented and estimates of incorporated concentrations are given.