Studies of heteroepitaxial growth of thin II-VI semiconductor layers by sequential ultrahigh vacuum dosing

An in situ molecular-level study of material growth using a binary reaction sequence of hydride and metalorganic precursors is presented. The study us ed a model material system of CdS/ZnSe(100) and focused on the material che mistry of heteroepitaxy growth. In the growth process, dimethylcadmium and H2S precursors were sequentially dosed onto a c(2 x 2) ZnSe(100) substrate under high-vacuum conditions. At temperatures of similar to 300 K, saturate d chemisorption of a Cd and a S monolayer occurred during each cycle of the binary reaction sequence. Characterization of the growth surface was accom plished in the growth chamber using Auger electron spectroscopy, x-ray phot oelectron spectroscopy and low-energy ion scattering spectroscopy fbr probi ng surface chemical composition and low-energy electron diffraction for det ermining surface order. These measurements showed layer-by-layer growth at a substrate temperature of similar to 300 K, yielding on ordered stoichiome tric CdS film. Strong variations in the composition of the grown surface la yer were observed at different substrate temperatures: these variations wer e found to be related to the temperature dependence of the precursor reacti ons with the growth surfaces. (C) 2000 American Vacuum Society. [S0734-2101 (00)01802-9].