Electrical and Optical Properties of Chromium Doped GaP

Abstract

Subject classification: 71.55Eq; S7.11The electrical properties of p-type GaP : Cr : Zn and n-type GaP : Cr : S samples have been studied using Deep Level Transient Spectroscopy (DLTS). In GaP : Cr : Zn a deep hole emitting level is detected with a thermal activation energy of E v þ 0.48 eV and attributed to the Cr 3þ/4þ donor level of substitutional Cr Ga . In GaP : Cr : S a deep electron emitting level is detected at E c À 0.30 eV and attributed to the Cr þ/2þ double acceptor level of Cr Ga . The emission rates of both levels are found to be electric field dependent which can be fitted by a Poole-Frenkel model. Deep Level Optical Spectroscopy (DLOS) measurements were performed on both levels in the filled as well as in their emptied state. The Frank-Condon shifts were estimated from these measurements. The spectral shape of these DLOS spectra is discussed as due to photoionization transitions.