High-purity GaAs grown by molecular-beam epitaxy

Abstract
We have grown high‐purity GaAs on (100), (311)A, and (311)B orientations by molecular‐beam epitaxy (MBE). While undoped GaAs grown on (100) and (311)A are typically p type, growth on (311)B orientation has yielded n type with a liquid‐nitrogen electron mobility of 1.3×105 cm2 V1 s1, which is among the highest mobilities reported for MBE‐grown materials. Low‐temperature photoluminescence showed well‐resolved impurity bound exciton peaks consistent with electrical results. The possible incorporations of impurities, especially carbon, are discussed. Our work demonstrates that the previously reported undoped p‐type GaAs(100) are compensated.