The solubility and diffusivity of In in CdTe

Abstract

The solubility and diffusivity of In in CdTe has been investigated in the temperature range 200-850 degrees C, under Cd-rich and Te-rich conditions, using a radiotracer method. The diffusivity is independent of In concentration and below 400 degrees C is also largely independent of temperature. Above 400 degrees C the solubility and diffusivity depend on both temperature and non-stoichiometry. At Te saturation D(In)=6.48*10-4 exp(-1.15 eV/kT) cm2 s-1 and at Cd saturation D(In)=117 exp(-2.21 eV/kT) cm2 s-1. The results are discussed in terms of the defect chemistry of CdTe.

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

“…The radiometry data [44][45][46][47] became a base for the equation lnD 0 = (11 ± 1) DE a À (21 ± 2), R 2 = 0.85 that is in good agreement with Arrhenius' parameters for D In [23,43,48] obtained by other techniques (Fig. 4a, dashed line).…”

“…Reviewing the data in Table 2, one should pay attention to evidence pointing towards a change in the slope of the Arrhenius' correlation within a certain temperature range (at 548 [37] and 614 K [38] for Hg diffusion; at 743 [42] and 673 K [47] for Ga and In, correspondingly, at 928 K [53] and at 753 K [54] for O and S, correspondingly). The underlying reason for these observations is not clear, however, it may be connected with structural transformations in the lattice.…”

“…Though three temperature dependencies of In, Ga and Tl diffusivity intersect in the same point at T = 1390 K (i.e. in CdTe molten state), it can't be a solid base for a conclusion about the data fit to the NMR [37,38] Hg [39,40] *Zn [35] Zn [36,59] ln(D 0 , cm 2 /s) [24,26,27] Cu [25,28,29] *Ag [30] Ag [28,31] Au [34] ln(D Li [22] Na [23] Al [22] *Ga [41,42] In [23,43,48] *In [44][45][46][47] *Tl [49] *Ge [50] *Sn [51] ln(D T 0 (a) (b) Fig. 4 (a) The plot of the ln D 0 versus DE a for the diffusivity of the Groups I, III and IV impurities in CdTe crystals and thin films.…”

“…Besides, it is known that impurities in CdTe can be trapped by tellurium (or cadmium) precipitates as well as by inclusions due to segregation during annealing or quenching; [59,72] that can be one of the reasons for the complicated profiles. In some cases, the experimental results below certain critical temperatures are not described by the Arrhenius' plot which was extrapolated from the hightemperature data (e.g., see [16,47,64] ). It is thus difficult to rely upon the best linear approximation.…”

The effect of the series resistance on the photovoltaic properties of In-doped CdTe( p ) thin film homojunction structure

“…The effect of Indium doping on the electrical characteristics ofCdTe thin film has been studied for many years [3]. Recently, Hussien et al [4] revealed the possibility of controlled doping with Indium for net donor concentration between 10 15 and 10 18 cm-3 in CdTe using the annealing temperature as a control factor.…”