The observation of a sharp peak in the deep-level photoconductivity spectrum of GaAs(Cr) due to the Cr2+(5T2-5E) 'intracentre' transition

Abstract

The 0.82 eV intracentre transition of Cr²⁺(⁵T₂ to ⁵E) in GaAs is observed as a very sharp peak in the low-temperature photoconductivity response. The dependence of the photoconductivity on temperature and electric field is discussed and a comparison is made with the corresponding line in absorption. The results demonstrate that the ⁵E excited state is at an energy above the band edge and that photoconductivity arises from auto-ionisation of the ⁵E excited state whereby an electron is ejected into the conduction band continuum.