Growth and Analysis of Nanostructured CuInSe2-ZnIn2Se4 Solid Solutions: Their Electrical and Photoelectrical Properties

Abstract

We report growth and investigation of structural and (photo−)electrical properties of CuInSe2– ZnIn2Se4 semiconductor crystals, grown by the horizontal Bridgman method. Their optical bandgap was evaluated from the absorption spectra. It increased monotonously from 1eV up to 1.08 eV at 300 K with increasing amount of ZnIn2Se4 in the range of 5–20 mol%. All crystals had n-type electrical conductivity. The solid solutions containing 5–10 mol% ZnIn2Se4 had demonstrated weak temperature dependence of the electrical conductivity, high electron density and low photoconductivity. This evidences their nearly degenerate state. In the crystals with 15 and 20 mol% ZnIn2Se4 a variable range hopping conduction mechanism was found to dominate between ∼30K and 110K. Above 130K it was changed by a thermally activated conductivity. The donor activation energy for the samples with 15 and 20 mol% ZnIn2Se4 were 0.018 eV and 0.04 eV, respectively. The characteristic feature of the spectral distribution of their photoconductivity at 30-70K is presence of a narrow peak at 1160 – 1190nm.