Capped versus capless heat treatment of molecular beam epitaxial GaAs

Abstract
Both capless and Si3N4 capped annealing of molecular beam epitaxial n-GaAs were investigated by photoluminescence and computerized deep level spectroscopy. It was found that the 1.507-eV emission bands (defect exciton) and the 1.4934-eV (carbon) and the 0.83-eV (EL2) electron trap are greatly enhanced after Si3N4 encapsulated annealing at 700 °C. These features were not observed in capless annealed material. It is concluded that capless annealing using an InAs ambient can avoid surface impurity, drive in, and stress effects in the MBE film. In addition, Si3N4 capping causes surface topographic degradation on annealing, whereas capless annealing does not.