Thermal stress and defect reduction in undercut GaAs on Si substrate

Results of a TCA (thermal cycle annealing) experiment on UCGAS (undercut GaAs on Si) in which the GaAs/Si interface is partially etched to separate the GaAs layer from the substrate are reported. The structure is developed to reduce the thermal stress in GaAs grown on Si. A drastic EPD (etch pit density) reduction by TCA is observed by eliminating the GaAs/Si interface which acts as a dislocation source, and a dislocation-free region about 6 μm wide is obtained at the edge of the structure. Therefore, it is possible to eliminate both the thermal stress and the dislocations at the edge of the UCGAS.