Sb-flow-rate dependence of triple-period (TP)-A-type atomic-ordering in Ga 0.5In 0.5P grown by metalorganic-vapor-phase epitaxy

Abstract

The Sb-flow-rate dependence of atomic ordering in Ga 0.5In 0.5P grown at about 650°C on (0 0 1) GaAs substrates by metalorganic-vapor-phase epitaxy was studied. The Sb-flow-rate ratio f R (defined as [TDMASb]/([PH 3]+[TDMASb])) was varied in a small Sb-flow-rate-ratio regime ( f R⩽1%), where [TDMASb] and [PH 3] indicate the Sb-source-gas (TDMASb: Tris-dimethy-lamino-antimony) flow-rate and phosphine flow-rate, respectively. CuPt-B-type atomic ordering appeared for 0%⩽ f R⩽0.015%. For f R≈0.015%, a mixture of CuPt-B and TP (triple-period)-A ordering domains is formed, while for f R⩽0.05%, TP-A ordering was dominant. Based on these results, it was concluded that the surface structure changed from (2×1) to (2×3) in-between f R=0.015% and 0.05%. The Sb-composition in solid ((1− y) Sb, where 1− y is that in Ga 0.5In 0.5P y Sb 1− y ) tended to saturate for f R⩾0.05%. It is noted that TP-A-type ordering appeared in the Sb-composition saturation regime; (1– y) Sb was 0.73% at f R≈0.050% and, 1.6% at f R≈1.0%, respectively. Thus, Sb incorporation appears to be influenced by the surface reconstruction.