Optical, electronic and magnetic properties of the dilute magnetic semiconductor Mn:CuInte₂

Abstract

CuInTe₂ and CuInSe₂ are direct bandgap ternary chalcopyrite (I-III-VI₂) semiconductors which are the simplest ternary analogs of the II-VI zincblende compounds. Some of the chalcopyrites exhibit nonlinear optical properties which make them good candidates for optical device technology. We have done preliminary studies on the influence of Mn²⁺ on the optical, transport and magnetic properties of CuInTe₂ in analog to previous stud-ies of Mn:CdTe etc. Bulk polycrystalline p-type samples, with up to 12% Mn substi-tution, have been examined with polarized light microscopy, x-ray energy dispersive analysis, optical spectrometry, van der Pauw technique and SQuID magnetometer mea-surements. From the metallurgical studies, Mn is found to substitute for Cu but not In. The bandgap of Mn:CuInTe₂ is larger than 0.92 eV. Most of our samples show phonon limited mobility, with the highest mobility occurring at ≈75K. Without Mn substitu-tion, CuInTe₂(Se₂) is diamagnetic. Samples with 3% Mn substitution in Cu sites are paramagnetic. At higher Mn concentration (3% < x < 12%), the (Cu_1-xMn_x)InTe₂ sam-ples show antiferromagnetic coupling and a measured effective magnetic moment up to ≈5.4 μB/Mn atom. Samples with attempted Mn substitution in In sites (from 3% to 9%) show anomalous magnetic behavior at low temperatures.