SYNTHESIS AND CHARACTERIZATION OF SOME MIXED ALKYL THIOCARBAMATES OF GALLIUM AND INDIUM, PRECURSORS FOR III/IV-MATERIALS - THE X-RAY SINGLE-CRYSTAL STRUCTURES OF DIMETHYLINDIUM AND DIETHYLINDIUM DIETHYLDITHIOCARBAMATES

A series of mixed alkyl/dithiocarbamates of the general formula R(2)MS(2)CNEt(2) (M = In or Ga and R = Me, Et, or neopentyl) have been prepared and characterized. The indium complexes are well-defined crystalline solids, and X-ray single-crystal structures are reported for the methyl and ethyl compounds. Both compounds have S2C2 coordination at indium, and all bond lengths and angles are in the normal range. The gallium complexes are all liquids. The indium compounds ha ve been used to successfully deposit thin films of various phases of InxSy by low-pressure MOCVD onto GaAs(100) substrates. The methyl complex deposits orthorhombic InS39 and monoclinic In6S739 phases between 425 and 400 degrees C; growth at 325 degrees C resulted in the cubic beta-In2S3 phase. In contrast the ethyl compound deposits monophasic beta-In2S3 over the 400-350 degrees C, the neopentyl indium compound deposits In6S7 at 400 and 375 degrees C with the presence of a small amount of the beta-In2S3. Preliminary results of deposition experiments with the gallium precursors were less successful, and only very thin films were grown.