INSITU MONITORING OF ANTIPHASE DOMAIN EVOLUTION DURING ATOMIC LAYER MBE (ALMBE) AND MBE GROWTH OF GAAS/SI(001) BY REFLECTANCE DIFFERENCE

Reflectance difference technique is used to in-situ monitor the antiphase domain (APD) annihilation process during atomic layer MBE and MBE growth of GaAs on Si 2-degrees and 4-degrees off (001) towards <110>. We show that this technique is able to provide quantitative information on the domain evolution. Experimental data obtained with reflectance difference show that thin GaAs layers (typically 50-100 nm) are enough for achieving a single domain growth front. APD evolution is characterized by a process which starts at the onset of growth and is thickness dependent. We observe a fast APD evolution during growth of the first 500 angstrom thick layer followed by a slow step in case a single domain growth front has not yet been achieved. We find that the rate of the APD annihilation process depends on growth conditions, although the GaAs thickness (approximately 500 angstrom) at which kinetics changes is independent both on growth conditions and on density of steps in the starting surface (2-degrees and 4-degrees off (001) Si substrate). A possible relation between APD annihilation and lattice mismatch relaxation process is proposed based on these observations.