Semiinsulating CdTe

Experimental conditions for the growth of near stoichiometric high-resistivity CdTe single crystals with a minimal concentration of point defects are investigated. The position of the stoichiometric line in the pressure–temperature (P–T) phase diagram is evaluated from high-temperature in situ galvanomagnetic measurements. Calculations based on a model of two major native defects (Cd vacancy and Cd interstitial) show, that a very small variation of Cd pressure PCd results in a strong generation of uncompensated native defects. Modelling of room temperature carrier density dependence on the deep defect density NDD, PCd, and annealing temperature T shows, that the range of optimal PCd, at which high resistivity can be reached, broadens with increasing NDD or decreasing T. It is shown that at low T<450oC the deep defect density <1015 cm−3 is sufficient to grow the high-resistivity CdTe.