Surface reconstructions of GaAs(111)A and (111)B: A static surface phase study by reflection high-energy electron diffraction

Abstract

GaAs(111)A and (111)B static surface phase maps have been generated under a variety of substrate temperature and incident As4 flux conditions ranging from, respectively, 400-700°C, and from 1×1014 to 1×1016 molecules cm-2 s-1. For the case of GaAs(111)A only a (2×2) reconstruction was observed. However, four GaAs(111)B surface reconstructions were identified below a critical As 4 flux of JcAs4≅5×1015 molecules cm-2 s-1, viz.: (2×2); (1×1) LT; (19×19); and, (1×1)HT. Above J cAs4 the (19×19) surface phase was quenched, such that the (1×1)LT and (1×1)HT structures merged to form a single (1×1) phase. The transitions to and from each of these surface phases were found to be reversible, occurring at very specific substrate temperatures for a given incident As4 flux. The activation energies (εA) characterizing the reversible surface phase transitions were measured and compared with those on the GaAs(100) surface.