Kinetics of chemical beam epitaxy for high quality ZnS film growth

A comprehensive study is reported of the chemical and metalorganic molecular beam epitaxy (CBE/MOMBE) growth of ZnS on Si and GaAs(100) substrates for applications in advanced electroluminescent displays and for optoelectronic device integration on Si. Growth kinetics studies of conventional and photoassisted MOMBE and CBE using diethylzinc (DeZn) with H2S, di-isopropylsulfide (DipS) and a novel precursor, t-butyl mercaptan (t-BuSH), are reported. The results obtained indicated that the low temperature growth of ZnS using cracked DeZn and DipS was hindered. This was attributed to the reattachment of the alkyl radicals to surface growth sites, which resulted in a lower growth rate. However, by using uncracked DeZn and H2S or cracked DeZn and t-BuSH, this growth hindrance was removed by the surface reaction of hydrogen with the alkyl radicals. The addition of a thin CaF2 buffer layer was found to remarkably improve the growth of ZnS on Si.