Photoluminescence study of II–VI semiconductors by using radioactive 71As dopants

Abstract

By means of radioactive dopants, photoluminescence signals related to the respective chemical element are identified. In the present work, the isotope 71As ( t 1/2=65.3 h) which decays to 71Ge ( t 1/2=11.2 d) and subsequently to 71Ga was implanted into CdTe and ZnSe. In CdTe, the (D, A) transition related to the As Te acceptor is identified in agreement with the literature. In addition, a new (D, A) transition caused by a shallow Ga acceptor is identified. The corresponding acceptor level having an ionisation energy of E i=42 meV is still shallower than the effective-mass like state ( E i=57 meV). It is interpreted in terms of a 71Ga Te “antisite” defect in a Jahn–Teller distorted configuration. Ab initio calculations within the framework of density functional theory confirm the existence of a Jahn–Teller relaxed stable configuration for Ga Te. In ZnSe, no clear evidence of a (D, A As) transition is found, but like in CdTe, a new shallow acceptor is observed which is supposed to originate from a 71Ga Se defect.