EFFECT OF INTERFACE CHEMISTRY ON THE GROWTH OF ZNSE ON THE SI(100) SURFACE

Heteroepitaxial growth of compound semiconductors on Si surfaces is strongly affected by the chemical bonding at the interface. In this work, the growth of ZnSe on Si(100) surfaces by molecular-beam epitaxy has been investigated primarily by transmission electron microscopy (TEM). The dominant effect during interface formation is the tendency of Si and Se to react to form the amorphous compound SiSe2. By utilizing a number of growth techniques, we have been able to characterize the interface reaction and will describe methods where the reaction can be minimized. For ZnSe films grown at elevated temperatures, TEM images show the presence of a thick (approximately 100 nm) amorphous layer at the interface. For films deposited on Si(100) at room temperature and then crystallized by solid-phase epitaxy, we find no amorphous layer, but submonolayers of Se bonded to the Si surface may give rise to a misorientation between the Si and ZnSe crystals and to the large areas of twinned ZnSe that are observed. We discuss mechanisms for the tilt and for the observation that the twinned areas exist only in one of the two allowed configurations. The presence of an arsenic monolayer on the Si(100) surface prior to ZnSe growth is found to prevent any reaction between Si and Se and we find parallel epitaxial growth without any significant twinning. For growth of ZnSe either via room-temperature deposition and solid-phase epitaxy or on Si(100):As, we obtain very uniform films. This is in contrast to the situation for GaAs-on-Si epitaxy where island formation is dominant at comparable thicknesses. The use of ZnSe as an interlayer for GaAs-on-Si growth is proposed.