ZnSe heteroepitaxy on GaAs(001) and GaAs(110)

ZnSe heteroepitaxy on GaAs(0 0 1) and GaAs(1 1 0) substrates has been studied using molecular beam epitaxy. ZnSe films were grown on an atomically flat and low defect density hemoepitaxial GaAs(0 0 1) and GaAs(1 1 0) buffer. At the beginning of ZnSe growth on Zn-exposed GaAs(0 0 1)-beta(2 x 4) and on a GaAs(1 1 0) without Zn/Se-pre-deposition, RHEED oscillation was clearly observed. Low defect ZnSe films (defect density less than or equal to 10(5) cm(-2)) were also obtained. On the other hand, the ZnSe growth on Se exposure of both GaAs(0 01) and GaAs(1 I 0) surfaces was of islanding type and the defect densities were > 10(7) cm(-2). This result suggests the importance of interface chemistry, i.e. charge balance at the interface for ZnSe/GaAs heteroepitaxy. (C) 1998 Elsevier Science B.V. All rights reserved.