Temperature dependence of the reflected trimethylgallium flux intensity from a GaAs surface in metal-organic molecular beam epitaxy measured by mass spectrometry

Desorbed species from a substrate in metal-organic molecular beam epitaxy of GaAs using trimethylgallium (TMG) and As 4 were studied by mass spectrometry. The observed Ga-containing species were mainly reflected TMG at all substrate temperatures ranging from 290 to 650°C. The TMG reflection decreased with an increase in the substrate temperature up to 520°C, indicating a decomposition of TMG on the GaAs surface. Above 520°C, the reflection of TMG increased and showed a small maximum at about 600°C. The temperature dependence of the reflected TMG accounts for the reported anomalous temperature dependence of the growth rate of GaAs by MOMBE.