Deep Levels in GaAs Grown Using Superlattice Intermediate Layers on Si Substrates by MOCVD

Abstract

Deep levels in MOCVD-grown GaAs using superlattice intermediate layers on Si substrates were investigated by DLTS. Electron traps at 0.44 and 0.73 eV were observed in the undoped n-type GaAs grown on (100)2° off Si substrates while only a 0.73-eV trap was detected in GaAs on a GaAs substrate. The deep-level concentration in GaAs/Si and the capture cross section of a 0.44-eV trap decreased and the half width of the 0.44-eV trap increased with increasing GaAs thickness. The 0.73-eV trap concentration increased upon decreasing the curvature radius of the wafer by polishing the back side of the Si substrate; however, that of 0.44 eV was unchanged. These observations suggest that the 0.44-eV trap is due to Si-defect complexes changing their shapes with the GaAs thickness and that of 0.73 eV is caused by point defects.