ROLE OF GAS-PHASE ADDUCTS IN THE GROWTH OF GALLIUM-ARSENIDE BY METALORGANIC VAPOR-PHASE EPITAXY

Heating hex-5-enylarsine (hexAsH2) in the presence of trimethylgallium in solution produces methylenecyclopentane via a series of intermedia tes which include the adduct, [Me3Ga - As(hex)H2]. In the gas phase, t he major C6 product obtained from decomposition of hexAsH2 in the pres ence or absence of Me3Ga is hex-1-ene, indicating that the adduct is n ot formed to any significant extent in the gas phase. Calculations on [Me3Ga . AsH3] indicate that, whereas at room temperature the formatio n constant from Me3Ga and AsH3 is 0.24, the unfavorable entropy of thi s formation reaction ensures that the adduct will not be present to a significant extent in the gas phase at 900 K.