Role of ZnS buffer layers in growth of zincblende ZnO on GaAs substrates by metalorganic molecular-beam epitaxy

ZnS buffer layers were used to grow ZnO films on GaAs(001) substrates. The role of ZnS buffer layers in the growth of zincblende ZnO films on GaAs(001 ) substrates was investigated by atomic force microscopy. X-ray diffraction , and photoluminescence (PL) measurements. The optimization of the ZnS buff er layer thickness resulted in improvements of the surface morphology and c rystalline quality of ZnO films by homogeneous nucleation. With the optimiz ed ZnS buffer layer thickness of similar to 72 nm the surface root-mean-squ are roughness of the grown ZnO film was minimized to similar to 14 nm and t he deep-level PL intensity was reduced to 1/76 of the near-band edge PL int ensity at room temperature. (C) 2000 Elsevier Science B.V. All rights reser ved.