High-temperature investigation of ZnS:Ga and CdSe:Ga

High-temperature electrical conductivity (HTEC) as a function of temperature T and metal component vapour pressure pMe has been studied in ZnS:Ga and CdSe:Ga single crystals. The dependence of the concentration of free carriers n, on pMe and T may be expressed as n∼pMeαexp(-ΔE/kT). The activation energies ΔE from HTEC isobars and slope α values from HTEC isotherms were determined. CdSe:Ga HTEC isotherm is independent of pCd at temperatures lower than 850oC. Ga acts in CdSe as a donor with electroneutrality condition (ENC) and Ga mass balance condition (MBC) approximation n=[GaCd]∼[Ga]total. ZnS:Ga isotherms characterize with α∼0.5 at temperatures higher than 1070 deg. C. ENC and Ga MBC approximation [GaZn]=[(GaZnVZn)/]∼1/2[Ga]total characterize Ga self-compensation in ZnS:Ga