TRANSMISSION ELECTRON-MICROSCOPIC STUDIES OF N-TYPE AND P-TYPE DOPED CDTE

CdTe crystals doped with In, Ga, Mn and Cl prior to annealing in a Cd ambient are investigated by TEM. Precipitation of the dopant species is found to occur at native dislocations and in some cases is associated with dislocation climb. It is estimated that the limiting value of diffusivity for this combined process is almost-equal-to 10(-13) cm2 s-1 suggesting that it is controlled by Te self-diffusion. Cross-sectional TEM observations of post growth doped CdTe:P indicate that such doping procedures act to disrupt the near surface structure with the introduction of a complex tangle of dislocations and precipitates to a depth of almost-equal-to 20-mu-m. The diffusivity of P in CdTe at almost-equal-to 600-degrees-C is estimated to be almost-equal-to 5 x 10(-12) cm2 s-1.