MASS-SPECTROMETRIC STUDIES ON THE DECOMPOSITION OF TRIALKYLGALLIUM ON GAAS-SURFACES

The thermal decomposition of trimethylgallium [(CH3)3Ga] and triethylgallium [(C2H5)3Ga] on gallium arsenide (GaAs) surfaces was studied under an ultra-high vacuum using mass spectrometry. It was observed that the decomposition process of (CH3)3Ga and (C2H5)3Ga depends on the arsenic coverage of the substrate surface. On a (100)-oriented surface, increasing the arsenic coverage basically enhances the decomposition of (CH3)3Ga and (C2H5)3Ga to gallium atoms above 350 and 300-degrees-C, respectively. The decomposition of (CH3)3Ga proceeds by emitting CH3 radicals. On a surface with low arsenic coverage, the decomposition of (CH3)3Ga is imperfect and fewer than three methyl groups of alkylgallium are desorbed. On a (111)B-oriented surface, however, an increase in the surface arsenic coverage suppresses the decomposition of alkylgallium, which is different from the case for a (100) surface.