Reaction Mechanisms in the Thermal Decomposition of

Studies of the reaction mechanisms and rates of decomposition of triethylarsenic (TEAs) and diethylarsine (DEAsH) were measured by sampled gas infrared absorption spectroscopy. The thermal decomposition ofTEAs in a hydrogen gas ambient was observed to occur predominantly by ~-hydride limination in which ethylene (C2H4) and DEAsH are pro-duced. An activation energy of 45 kcal/mol is measured for the pyrolysis of the first As--C bond in the TEAs decom-position reaction. The pyrolysis of DEAsH was observed to produce both ethane (C2H6) and ethylene (C2H4) as by-products and was found to go to completion at temperatures about 500 ~ The decomposition ofDEAsH is concluded to be hetero-geneous ince the measured activation energy of 20.6 kcal/mol for the As--H bond pyrolysis is significantly lower than the As--H bond strength. In the interest of reducing the safety hazards associated with arsine gas, development of high purity organometal-lic group V sources would be of considerable benefit to growth of gallium arsenide (GaAs) by metalorganic chemi