Studies on the diffusion of zinc and iodine into CdTe

Electrical activity of iodine-diffused CdTe

“…The most significant conclusion that can be drawn from this series of measurements is that near the surface of the slice, which coincides with the region where the total iodine concentration is highest (diffusion regimes D 1 -D 3 with C 01 10 23 cm −3 ), 3 the iodine exists mainly in a neutral form in all cases, whereas deeper in the slice it exists in an electrically active form, either n-or p-type, depending on the treatment during the anneal. The maximum concentration observed in the C -V profiles was 10 17 cm −3 , which occurred when Cd was added to the diffusion source, so it can be assumed that when iodine is incorporated at concentrations higher than this it will exist in a neutral form unless the diffusion anneal takes place at a much higher temperature.…”

“…3 The projected room temperature diffusivity for the fastest part of the chlorine diffusion profiles (6 × 10 −25 cm 2 s −1 ) 7 was much lower than the corresponding one for iodine. 4 More recently, the diffusion of bromine into CdTe has been studied 8 and the concentration profiles which were measured using SIMS gave four-component profiles, yielding values of diffusivities and activation energies similar to those for the diffusion of iodine into CdTe.…”

“…3); in the other three cases a comparison was made with a constructed profile, which was obtained using interpolated values of D and C 0 obtained from the results published previously on the diffusion of iodine into CdTe. 3 The experimental details are given in Table 2.…”

“…The halogens have been used on a regular basis for some time as an n-type dopant in epitaxially grown devices, 2 but recent studies on the diffusion of iodine into CdTe from the vapour 3 have shown that complex diffusion profiles are produced which can be fitted satisfactorily by an empirical function composed of the sum of four complementary error functions. Four values of the diffusivities (D 1 -D 4 ) were obtained from each profile (see Fig.…”

Morphological effects and the diffusion of iodine in CdTe

“…During the diffusions, elemental iodine attacked the surface of the CdTe slices at temperatures >~ 100 °C, whereas CdI2 proved to be a suitable diffusion source at temperatures up to 600 °C. The iodine concentration profiles were composed of four parts which were described satisfactorily by a computer package consisting of the sum of four erfc functions, with all parts giving similar values for the activation energy ( ,~ 0.25 eV) [5]. Iodine surface concentrations of up to 1023 cm-3 were observed.…”