Studies on the diffusion of the halogens into CdTe

Abstract

A comparison of the diffusion of the halogens into CdTe is given. Diffusion anneals were carried out at selected temperatures in the range between 20 and 700 • C in evacuated silica ampoules using a diffusion source of CdI 2 , CdCl 2 or CdBr 2 under saturated vapour pressure conditions. The concentration profiles were measured using either a radiotracer sectioning (RTS) technique or secondary-ion mass spectrometry (SIMS).In most cases the profiles were found to be composed of four parts to which a computer package consisting of the sum of four complementary error functions (erfc) gave satisfactory fits to the data. This fitting method was purely empirical but it proved to be satisfactory to describe the diffusion profiles as well as to show how the diffusivities behaved with various parameters. Proposals explaining how this type of diffusion may occur are given.

Direct evidence of enhanced chlorine segregation at grain boundaries in polycrystalline CdTe thin films via three‐dimensional TOF‐SIMS imaging

“…The temperature of 400°C was chosen because this was the processing temperature of the CdCl 2 anneal used in this study. Analysis of the literature data for chlorine diffusion in CdTe reveals this is also the lowest temperature one would expect for chlorine diffusion of ~0.5 µm over 100 s—conditions likely to allow for equilibrium to be reached during cooling of a sample with 1‐µm‐sized grains after the CdCl 2 treatment . The diffusion data reported are for chlorine diffusion in single crystals; thus, grain‐boundary diffusion would likely be faster, suggesting a lower temperature should be chosen for use in Equation .…”

Empirical Correlations Between the Arrhenius’ Parameters of Impurities’ Diffusion Coefficients in CdTe Crystals

“…5a). However, only the data for chlorine diffusivity of [56,57] corresponded to the CEF and unexpectedly, far from CEF are proposed in [58] data for the bromine and iodine. The reason of that probably was shown in [71] where was obtained that the iodine diffusion caused heterogeneity of the CdTe, so forming a discontinuous phase of randomly distributed particles.…”

“…Thus, according to, [56][57][58][59] the profiles of halogens (Cl, Br, and I) comprise four parts that can be treated as the sum of four complementary error functions. Assuming that a change in the diffusivity mechanism is accompanied with the CEF correlation between pre-factors D 0 and DE a, all the Arrhenius' parameters were used for the graphical analysis (Fig.…”