ABINITIO MOLECULAR-ORBITAL STUDY OF THE THERMAL-DECOMPOSITION OF (CH3)HGA-ASH(CH3)

Ab initio molecular orbital calculations are used to investigate possible decomposition modes of the model sigma-bonded compound trans-(CH3)HGa-AsH(CH3). The computed bond energy of the Ga-As sigma bond is found to be approximately 58 kcal/mol compared to only 12 kcal/mol for a Ga:As dative bond in an adduct such as (CH3)H2Ga:AsH2(CH3). The Ga-As bond energy is found to be greater than the As-C bond energy, as well as the energy required for some intramolecular elimination processes. The consequences of these calculations for the thermal decomposition of the monomer (t-BU)2Ga-As(t-Bu)2, a possible precursor in the chemical vapor deposition of thin films of GaAs, are also discussed.