Effect of As2 physisorbed molecules on the photoemission current during growth: simulation of GaAs and GaAlAs deposition

We report results of atomic scale simulations on the dynamics of photoemission current during growth of GaAs and AlGaAs on (001) GaAs substrate. The physisorbed nature of As2 molecules is explicitly taken into account. The simulations show that under As-riche conditions, the maximum of photoemission current occurs at half monolayer growth as reported experimentally [H. Tsuda, J. Appl. Phys. 73 (1993) 226]. However, the oscillations show the same period reflection high-energy electron diffraction (RHEED). We also illustrate that photoemission oscillations can be used to determine the alloy composition of AlxG1−xAs in agreement with experimental results [J.J. Zinck, D.H. Chow, Appl. Phys. Lett. 66 (1995) 3524].