New Routes to II-VI Materials

Abstract

Zinc and cadmium dithiocarbamates were synthesized and used as single molecule precursors for the deposition of zinc or cadmium chalcogenides. The precursors were based on trimethylpropylenediamine including bis(trimethylpropylenediaminedithiocarbamato) zinc(lll)\cadmium(II) (3), (4) and methyl(trimethylpropylenediaminedithiocarbamato) zinc(III)\cadmium(II) (5), (6). These compounds have been chracterized by I. R, NMR ('H, 13Ca nd 11C3 d) and mass spectrometry. The c,ý sU*7 structures of bis(U-imethylpropylenediminedthiocarbamato)zinc(III) (3) and methyl- (ft-imethylpropylenediaminedithiocarbamato)cadmium (H) (6) have been determined, both compounds were polymeric. Thin films of zinc or cadmium sulfide by MOCVD method have been grown from (3), (4), (5) and (6). The cadmium compounds gave good films on both glass and GaAs substrates, but the films grown from corresponding zinc compounds were of poorer quality. Some t-butyl- and neopentyl(di-alkylamido)zinc compounds have been synthesized and characterized. Thin films of CdS, ZnS, CdZni-. S, and ZnO were grown by chemical bath deposition method. US films were deposited by using cadmium/ethylenediamine- /thiourea system whereas ZnS films were grown from zinc/ammonia/hydrazine/thiourea system. Films of ternary Cd,, Znl-,, S have been obtained by the addition of cadmium to the ZnS system. Calculation were carried out for the speciation of the solution for which US was deposited. Films of ZnO were deposited from solution containing zinc/ethylenediamine in presence of NaOH. The various parameters controlling the film quality, growth rates, morphology and crystallinity were investigated. The films deposited were characterized by several methods including scanning electron microscopy, tramission electron microscopy, X-ray powder diffraction, reflection high energy electron diffraction and the electronic spectroscopy.