ABSTRACT
The initial stages of self-organized InAs-dot formation on GaAs(OOl) have been investigated by reflectance-difference (RD) spectroscopy and reflection high-energy electron diffraction. The RD spectrum changes drastically at an InAs coverage of 0.1 monolayer (ML), which corresponds to a phase transition from the c(4×4) of the As-rich GaAs(001) to the (2×3) surface reconstruction. The RD signal at 2.56 eV is enhanced after 1.0-ML deposition of InAs. No significant change in the RD signal was observed at the onset of dot formation. Thus, the enhancement of the RD intensity at the 1.0-ML coverage indicates a phase transition of the wetting layer just before the dot formation. Furthermore, thermal annealing effects for the InAs dot structure are discussed.
