TERT-BUTYL(TRIFLUOROMETHYL)TELLURIUM - A NOVEL ORGANOMETALLIC CHEMICAL-VAPOR-DEPOSITION SOURCE FOR ZNTE

tert-Butyl(trifluoromethyl)tellurium, t-BuTeCF3, a novel organometalli c chemical vapor deposition source with high vapor pressure and low de compostion temperature, has been used in combination with dimethylzinc to deposit ZnTe in the temperature range 280-550-degrees-C. Films syn thesized below 400-degrees-C were heavily contaminated with ZnF2 Cryst allites ranging in size from 1 to 20 mum, depending upon the Te/Zn rat io and growth temperature. Above 400-degrees-C, relatively pure ZnTe f ilms were grown. Corresponding growth curves, measured in situ with a microbalance, exhibited a reduction of growth rate at the transition f rom ZnTe/ZnF2 to pure ZnTe. Growth with bis(trifluoromethyl)tellurium, (CF3)2Te, yielded ZnTe films without fluorine incorporation, but the growth rate was low even at 500-degrees-C. Pyrolysis of t-BuTeCF3 in h ydrogen and helium was studied by molecular beam mass spectroscopy at reduced pressure. A decomposition mechanism consistent with the experi mental observations is proposed. Decomposition begins at 230-degrees-C and occurs via two competing pathways: beta-hydrogen elimination and homolysis of the tert-butyl-Te bond. A high isobutene-to-isobutane rat io in the pyrolysis products suggests that beta-hydrogen elimination p revails over homolysis in the temperature range 250-450-degrees-C. Uns table(trifluoromethyl)tellurol, the primary product of beta-hydrogen e limination, decomposes to difluorocarbene, tellurium, and hydrogen flu oride. The difluorocarbene reacts with isobutene to yield 1,1-difluoro -2,2-dimethylcyclopropane or undergoes dimerization to tetrafluoroethe ne. The hydrogen fluoride reacts with dimethylzinc and leads to the Zn F2 contamination.