Surface reconstructions during growth of GaAs1−xBix alloys by molecular beam epitaxy

An in-situ electron diffraction study of surface reconstructions on (001) oriented GaAs1−xBix films has been carried out during growth by molecular beam epitaxy on GaAs substrates in the temperature range from 250 °C to 400 °C. We observe (1×3), (2×3) and (2×4) reconstructions on both GaAs and GaAs1−xBix surfaces. A (2×1) surface reconstruction is observed in the presence of Bi at low As2:Ga flux ratios. Higher Bi incorporation and stronger photoluminescence were observed for GaAs1−xBix films grown on (2×1) reconstructed surfaces, compared to samples grown on (1×3) surfaces. The location of the various surface phases has been mapped out as a function of temperature, Bi flux and As2:Ga flux ratio.

▶ We present a surface reconstruction phase diagram for GaAs1−xBix growth on GaAs (001) substrates. ▶ Surface phase diagram for GaAs (001) at low temperatures was obtained for comparison. ▶ Presence of Bi introduces a new (2×1) surface reconstruction at low As2:Ga flux ratios. ▶ GaAs1−xBix (2×1) phase is associated with higher Bi incorporation. ▶ Growth under this phase shows high layer uniformity and strong photoluminescence.