N- And P-Type Post-Growth Self-Doping Of Cdte Single Crystals

Abstract

Careful analysis of the Cd-Te P-T-X phase diagram, allows us to prepare conducting p- and n-type CdTe, by manipulating the native defect equilibria only, without resorting to external dopants. Quenching of CdTe, following its annealing in Te atmosphere at 350-550°C, leads to p-type conductivity with hole concentrations of approx. ~ 2 × 1016 cm-3. Slow cooling of the samples, after 550°C annealing in Te atmosphere, increases the hole concentration by one order of magnitude, as compared to quenching from the same temperature. We explain this increase by the defect reaction between donors VTe and Tei. Annealing in Cd atmosphere in the 350-550°C temperature range leads, in contrast to the annealing in Te atmosphere, to n-type conductivity with electron concentrations of approx. ~ 2 × 1016 cm-3. We ascribe this to annihilation of VCd as a result of Cdi diffusion. © 2000 Elsevier Science B.V