The heteroepitaxy of II-VI compounds on the non-isovalent substrates (ZnTe/Si)

At a heteroepitaxy of non-isovalent compounds with tetrahedral coordination of bonds it is necessary, that the conditions of epitaxy provided an inter face balance of valence electrons applicable to the tetrahedral configurati on of bonds. The counting of the number of valence electrons was considered with Si-ZnTe interface formation. For preservation tetrahedral coordinatio n the numbers of bonds of Zn and of Te with silicon should be equal. This c ondition will not hold for the most orientations of substrate surface. It i s also necessary to allow for the presence of surfactants (As), which have a different valency from that of silicon. The arsenic on Si(013) and on Si( 113) at temperatures up to 870 K formed adsorption layers close to single m onolayers. Tellurium and zinc in contrast to arsenic, are adsorbed at tempe ratures of ZnTe nucleating and growth (570-670 K) in small numbers (<0.1 hi t) even directly in tellurium and zinc molecular fluxes. The ZnTe nucleatin g and growth takes place from an adsorptive low-density layer. The 3D-islan d formation occurs at the initial stages of ZnTe film growth on Si(013) and Si(113) treated by arsenic. The composition of critical size precursors of film islands was investigated by the variation of Zn and Te molecular beam densities. The precursor of Zn/Te ratio is one on Si(113):As surfaces and is two on Si(013):As surfaces. The CdTe/ZnTe/ Si epitaxial heterostructures on Si(013) and Si(113) substrates were grown by MBE. The epitaxial films h ad a substrate orientation. The lower structural perfection is observed nea r the interface in ZnTe films on Si(113):As. It corresponds to the results of the implemented approach. (C) 2000 Elsevier Science S.A. All rights rese rved.