IN-SITU MONITORING AND CONTROL OF SURFACE PROCESSES IN METALORGANIC VAPOR-PHASE EPITAXY BY SURFACE PHOTOABSORPTION

In-situ surface photo-absorption (SPA) was applied to study the dynamic surface processes and the static surface structures during metalorganic vapor phase epitaxy (MOVPE). The static surface structure in MOVPE can be analyzed by the spectrum in near-ultra-violet and visible regions, which comprises an anisotropic dielectric response due to the surface dimer bond as well as an isotropic response probably due to the surface back-bond. Time-resolved spectra showing dynamic changes of the surface can be measured by the use of optical multichannel analyzer. The rate of surface decomposition of source molecule and the rate of desorption of surface species were measured as the change of reflectivity at a fixed wavelength. The decomposition of source molecules was characterized quantitatively, and a correlation between the rate of desorption of group V atoms and the bond strength of a surface back-bond was found. During heteroepitaxy, the surface exchange of group V atom was monitored in situ, and the growth was accordingly controlled to suppress this exchange reaction and obtain a compositionally abrupt interface.