ELECTRON COUNTING MONTE-CARLO SIMULATION OF THE STRUCTURAL-CHANGE OF THE GAAS(001)-C(4X4) SURFACE DURING GA PREDEPOSITION

An electron counting Monte Carlo (ECMC) simulation is performed to inv estigate the structural change of As-rich GaAs(001)-c(4 x 4) surfaces during Ca predeposition, incorporating the As desorption process as a function of Ga adatom coverage based on ab initio calculations. The EC MC simulation results indicate that predepositing 0.5 monolayers of Ga on the GaAs(001)-c(4 x 4) surface induces As desorption and reduces e ffective As coverage theta(As) to 1.25, where four Ga dimers and two A s dimers co-exist in the (4 x 4) surface unit cell used in this simula tion. Subsequent equilibration of this surface changes its structure t o (2 x 4)-like surface with theta(As) = 0.75 and one As-dimer row and three missing As-dimer rows. These simulated results successfully give one possible interpretation to some puzzling questions in experimenta l results.