Theoretical study of MBE growth of indium gallium arsenide semiconductor compound on gallium arsenide substrate

The theoretical study of Molecular Beam Epitaxy allows us to model and construct an experiment with the same conditions. Growth modeling investigates compound semiconductor characteristics during the MBE growth which can achieve the best results to control the quality of growth. Growth modeling also is less expensive and faster than experiments. The wide variation in the band-gap and lattice constants between InAs and GaAs is a subject for a variety of optical and electronic device applications involving InGaAs/GaAs systems. In this material system, the perfection is intrinsically controlled by the surface segregation of In due to its larger atomic size compared to Ga. In this work, a rate equation model is developed including several surface processes such as segregation from the crystalline layer to a surface riding In segregated layer and incorporation from the segregated In layer to crystalline layer and gallium desorption to surface layer. The rate of the processes are assumed Arrhenius type with concentration dependent activation energies. The simulated In incorporation coefficient versus substrate temperature is in excellent agreement with the experimental data [1] for various As overpressure. For a constant As overpressure, In incorporation decreases with increasing temperature. For a constant temperature, In incorporation increases with increasing As overpressure. The In desorption versus time results from experiments and our simulation match very well. The desorption process has two components, one arising from the physisorbed layer of In and the other from the surface of the crystal. The activation energy for these processes for an isolated adatom are 0.18 eV and 2.6 eV, respectively. These observations are explained based on the interplay of competing surface processes such as segregation and incorporation