Defect analyses of selective epitaxial grown GaAs on STI patterned (0 0 1) Si substrates

•The defects of GaAs layers grown on patterned Si (001) substrates were evaluated.•Defects and strain relaxation process were examined via STEM and NBD measurement.•The residual compressive stress in GaAs layers resulted from STI oxide side walls.

The defects of GaAs layers grown on Si (001) substrate with patterned SiO2 structures were investigated using transmission electron microscopy. The compressive strain along the 〈110〉 direction was induced in selectively grown GaAs epilayers.The defects such as stacking faults or microtwins were trapped near the GaAs/Si interface, over which defect free GaAs regions were formed from the middle of trench walls. It is suggested that the residual compressive strain in defect free GaAs layers is due to the patterned SiO2 structures.