Influence of lattice mismatch and growth rate on the decay of RHEED oscillation in the case of InGaAs/GaAs growth

The intensity decay of the oscillation of the reflection high-energy electr on diffraction pattern's specular beam is analysed during the molecular bea m epitaxy of strained InGaAs/GaAs heteroepitaxial structures. The oscillati ons' amplitude was found to decrease exponentially with time during the InG aAs growth. Further, the decay time constant decreases with InAs mole fract ion, indicating that the lattice strain increases islanding during growth. A simple semi-quantitative model based on the growth front roughening is fo rmulated to explain the results. Assuming that the oscillation decay is rel ated partly to the strain and partly due to kinetic effects during growth, a decay component that is solely due to strain can be separated; we find th at the onset of increased roughening due to the misfit strain component rou ghly corresponds to the equilibrium critical layer thickness for misfit dis location generation.