RHEED AND RD MONITORING OF CBE USING TEG AND TBA AS PRECURSORS

We have studied chemical beam epitaxy (CBE) of GaAs by reflection high-energy electron diffraction (RHEED) and reflectance-difference (RD). The precursors used are triethylgallium (TEG) and tertiarybutylarsine (TBA). From the period of the RHEED oscillations the growth rate as a function of the temperature has been obtained. However, in spite of excellent RHEED oscillations no unambiguous oscillatory behaviour in the corresponding RD data was resolved. During pure TEG exposure of the GaAs surface characteristic RD features have been obtained and found related to specific RHEED reconstructions. Furthermore, a study has also been made of how excess Ga, accumulated on the surface during extended TEG exposure, is consumed by subsequent TBA injection.