L. Türn

High temperature electrical conductivity of undoped ZnS

High temperature defect equilibrium (HTDE) in ZnS was analysed to study the conditions of making p-type material. High temperature electrical conductivity (HTEC) under defined component vapour pressure was investigated in undoped ZnS in the temperature range from 600°C to 1140°C. HTEC measurements were carried out using a two-zone resistance furnace and a vacuum sealed quartz ampoule with four sealed tungsten or graphite electrodes. All ZnS HTEC isotherms can be divided into three regions. The high zinc vapour pressure (pz n ) and the high sulphur vapour pressure (ps 2 ) regions are characterized by dominant native donors. In the ZnS HTDE model, antistructure disorder is dominating at high ps 2 values, similar to CdS and CdTe HTDE models. Changes occur at low pz n or at low ps 2 values. The increase of HTEC at low pz n or at low ps 2 values is explained by the existence of the p-type area in this region. This p-type area appears in the total range of temperature investigated.