The site and pseudodonor character of manganese in single-crystal lead telluride

Abstract

From the analysis of electron paramagnetic resonance (EPR) spectra and the electrical characteristics of as-grown, long-period 'annealed' at room temperature and laser annealed PbTe:Mn single crystals with Mn content NMN approximately=2-7*1018 cm-3 the authors infer that Mn2+ ions in as-grown crystals are incorporated partly interstitially and partly in the metal sublattice sites. In crystals with NMn>or approximately=2*1019 cm-3 Mn ions tend to form clusters. In such cases manganese behaves as an amphoteric impurity, as a small amount of Mn ions in the metal sublattice points cannot compensate for the large number of Pb vacancies (NPb approximately 5*1019 cm-3) that act as acceptors. When creating the conditions that promote migration of Mn ions into PbTe metal sublattice points (long-period 'annealing' at T=300 K, IR laser annealing) which is tested by hyperfine structure and superhyperfine structure of EPR spectra, the Mn2+ ions act as pseudodonors, compensating for two holes from each lead vacancy. The electron concentration in such a case is attributed to Te vacancies, which are donors. The spin-Hamiltonian constants were determined at T=20 K for as-grown, long-period 'annealed' and laser annealed PbTe:Mn crystals.