Low-resistance contacts to p-type Li-diffused CdTe

Abstract

Reproducible low-resistance contacts to p-type CdTe single crystals have been made by diffusion of Li into the CdTe surface before evaporation of Au as the contact metal. Diffusion produces a surface hole density of about 1019 cm−3 at room temperature; this results in a contact resistivity of the order of 0.01 Ω cm2, the lowest value reported to date for p-type CdTe. The high diffusivity of Li results in a degradation of the contacts even at room temperature, with the degradation rate critically dependent on the temperature used for Li diffusion. The optimum temperature appears to be about 280 °C; contacts formed on surfaces diffused with Li at this temperature show a contact resistivity of 0.025 Ω cm2 after 5 months.