Effect of thermal cyclic growth on deep levels in AlGaAsSi heterostructures grown by MOCVD

Single crystalline epitaxial layers of Al0.22Ga0.78As have been grown on Si substrates. Silicon diffusion in the heteroepitaxial layers has been explained by a pipe diffusion model and a gas phase reaction model. The dislocation bending at the AlGaAsSi interfaces has been explained in terms of electrical potential difference, thermal stress and point defect complexes. The Schottky diode characteristics of AlGaAsSi have been studied and the ideality factor (n) and Schottky barrier height (φb) estimated in the present study were 1.2 and 0.89 eV, respectively. Capture cross-sections, activation energies and concentrations of the deep levels have been calculated by deep level transient spectroscopy. Two deep levels with thermal emission energies of 0.43 and 0.64 eV have been observed in the 900°C thermal cycle annealed samples. Influence of silicon complex defects on the nature of the deep levels has been addressed.