An ab initio-based approach to phase diagram calculations for GaAs(0 0 1)-(2 × 4)γ surfaces

✍ Scribed by Tomonori Ito; Toru Akiyama; Kohji Nakamura

• Publisher: Elsevier Science
• Year: 2008
• Tongue: English
• Weight: 729 KB
• Volume: 254
• Category: Article
• ISSN: 0169-4332
• DOI: 10.1016/j.apsusc.2008.01.133

✦ Synopsis

Surface phase diagram of recently proposed GaAs(0 0 1)-(2 Â 4)g is systematically investigated by using our ab initio-based approach. We focus on the (4 Â 7) domain consisting of c(4 Â 4)-like and (2 Â 4)-like regions to clarify surface dimer constituents as functions of temperature T and As (As 2 and As 4 ) pressure p As by comparing chemical potentials of surface dimers in the vapor phase with that on the surface. The calculated results under As 4 imply that Ga dimers in the c(4 Â 4)-like region tend to become stable with increase of temperature and appear at the conventional growth condition such as T $ 800 K and p As $ 10 À6 Torr, while the (2 Â 4)-like region favors As dimers. This is consistent with temperature dependence of change in surface dimer constituents on the c(4 Â 4) and (2 Â 4)b2 clarified in our previous study. Furthermore, the surface phase transition from the c(4 Â 4) to (2 Â 4)b2 via (2 Â 4)g is discussed on the basis of the phase diagram obtained in this study.