Modification of band gap in surface layer in Cd1-xZnxTe by YAG:Nd+3 laser radiation

Abstract

A mechanism of formation of graded band-gap based on Thermogradient Effect (TGE) is proposed in Cd1-xZnxTe at irradiation by second harmonic of a Q-switched YAG:Nd laser. According to the effect, the interstitial atoms of Cd (Cdi) in Cd1-xZnxTe move along the temperature gradient while the Cd vacancies (VCd) and Zn atoms - in the opposite direction, into the bulk of the semiconductor where temperature is lower. Photoluminescence (PL) spectra studied at 5 K show that concentration of Zn atoms increases due to aggregation of VCd with Zn after laser irradiation. Formation of a graded band-gap in Cd1-xZnxTe crystal at irradiation by second harmonica of YAG:Nd laser by is shown to be possible.