ZnSeのMOMBEの成長におけるGaAs基板硫黄処理効果

概要

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II-VI wide-gap semiconductors, such as ZnSe, CdS and ZnS are very promising materials for the potential application to optoelectronic devices which cover from blue to ultra violet spectral region. To this end, it is important to develop the fabrication technique. Although epilayers of good quality have been grown on GaAs substrates by molecular beam epitaxy (MBE), metalorganic molecular beam epitaxy (MOMBE) and organometallic vapour phase epitaxy (OMVPE), it is still difficult to obtain epilayers of device quality. Recently, we have found that the surface pretreatment technique plays an important role in fabricating high-quality epilayers through in-situ RHEED monitoring in the MOMBE system. In this paper, we report that layer-by-layer or two-dimensional growth of ZnSe is successfully achieved from an initial stage of growth, if the GaAs is pretreated by (NH4)2Sx, solution. Furthermore, we also report that not only the ZnSe/GaAs interface properties but also the optical qualities of ZnSe and ZnS epilayers are greatly improved by this pretreatment.