STUDIES ON THE DIFFUSION OF ZINC AND IODINE INTO CDTE

Studies on the diffusion of iodine and zinc into CdTe are reported. Ea ch iodine profile was divided up into four distinct regions and descri bed mathematically toy a function consisting of the sum of four comple mentary error functions. When plotted on an Arrhenius graph, the diffu sivities gave four straight line relationships with similar slopes and the Arrhenius parameters for the fastest component of D-01 = (7+/-3) . 10(-11) cm(2) s(-1) and E(1) = (0.21 +/- 0.05) eV. When extrapolated down to 20 degrees C this gave a diffusivity of 10(-14) cm(2) s(-1), indicating that when iodine is diffused from the vapor it is not suita ble as a long term stable dopant in devices where sharp impurity profi les are required. In the case of the zinc diffusions, each profile can be divided into two parts and was fitted satisfactorily by the sum of two complementary error functions giving two values of the diffusivit ies: D-slow due to zinc diffusion into the slice from the vapor and D- fast due to interdiffusion between a surface layer of ZnxCd1-xTe forme d on the slice and the remaining CdTe.