ADSORPTION AND DECOMPOSITION OF TMGA ON GAAS(100)

The adsorption and decomposition of trimethylgallium (TMGa) on the gallium-rich GaAs(100) surface has been studied using electron-energy-loss spectroscopy (EELS) and Auger electron spectroscopy (AES). It was found that the first layer of TMGa already decomposes at 100 K. Further dosing the surface resulted in condensation of TMGa. At room temperature only chemisorbed TMGa was found, with a saturation coverage of 0.3+/-0.1 monolayer gallium. We found the adsorbate species to be monomethylgallium and/or dimethylgallium. We also studied the adsorption and decomposition of iodomethane, as well as the adsorption of hydrogen. Coadsorption experiments showed that only TMGa could replace or react with the adsorbed hydrogen atoms. In the case of CH3I almost no coadsorption or reaction occurred.