Compensation center of Cr3+ in GaAs codoped with Cr and In for obtaining a semi-insulating property

Abstract

The dependences of Cr2+ and Cr3+ electron paramagnetic resonance (EPR) signals as a function of Cr concentration have been investigated in conjunction with clarifying the atomic configuration for obtaining semi-insulating properties in a vertical gradient freeze (VGF)-GaAs single crystal codoped with Cr and In (VGF-GaAs:Cr,In). Cr2+ EPR signals are observed in both samples of semi-insulating and semiconducting GaAs: Cr,In single crystals, whereas Cr3+ EPR signals can be observed only in semi-insulating samples. The semi-insulating properties become obvious when increasing the intensity of Cr3+ and Cr2+ EPR signals in VGF-GaAs:Cr,In crystals. Isolated Cr-Ga(3+) ions play an important role in GaAs as a charge compensation center for obtaining semi-insulating property. Copyright (C) 1996 Elsevier Science Ltd