Thermal annealing effects on the defect and stress reduction in undercut GaAs on Si

This paper describes the thermal annealing effects of UCGAS (undercut GaAs on Si) in which the GaAs layer is partially separated from the Si substrate by the post-growth lateral etching. A drastic defect reduction is found in UCGAS after annealing at 800 °C, while no significant EPD reduction is obtained in the planar region. The photoluminescence intensity ratio of planar GaAs on Si and UCGAS {PL(UCGAS)/PL(planar)} is about 3 and more than 10 before and after the annealing at 800 °C, respectively. A model which assumes the GaAs/Si interface to be a dislocation source predicts that the high temperature annealing is effective in reducing dislocation density in UCGAS.