REFLECTION HIGH-ENERGY ELECTRON-DIFFRACTION AND REFLECTANCE DIFFERENCE STUDIES OF SURFACE ANISOTROPY IN INGAAS CHEMICAL BEAM EPITAXY ON FLAT AND VICINAL (001)GAAS

InGaAs quantum wells (QWs) were grown in a chemical beam epitaxy (CBE) machine with trimethylindium (TMI), triethylgallium (TEG) and tertiar ybutylarsine (TBA) as precursors. Growth was monitored in-situ by refl ectance difference (RD) and reflection high energy electron diffractio n (RHEED), on both flat and vicinal (2-degrees off in the [111]A direc tion) (001)GaAs substrates. The RD was monitored at 632.8 nm. At this wavelength the RD signal from a GaAs surface is primarily related to t he absorption by Ga dimers. When InGaAs had been grown, both the avera ge RD signal and the amplitude of the RD oscillations for the subseque nt growth of GaAs increased significantly, compared to GaAs growth on GaAs. This In influence was found to persist even after the growth of 20-30 ML of pure GaAs. As a result we were able to monitor growth osci llations with RD and RHEED simultaneously during growth of quantum wel ls of InGaAs in GaAs. As a conclusion to these observations we suggest that the group III dimer bond concentration, detected in the RD signa l, increases.