It was shown that the transient ion drift method, which was based upon studying the junction capacitance under a constant reverse bias, could be used not only for the measurement of the diffusion coefficient of mobile impurities, but also for the estimation of the concentration of mobile species as part of the total dopant density. This was demonstrated for CdTe which was contaminated by Cu, or deliberately doped with Li or Ag. It was also shown that the transient ion drift method could be used if the mobile ions were major dopants. This was demonstrated by using Schottky barriers on CdTe, and p-n junction devices in HgCdTe and CuInSe2. The values which were obtained for the diffusion coefficients of Cu in CuInSe2 and for Li, Ag and Cu in CdTe (tables 1 and 2) agreed well with reported values which had been obtained by using other methods. It was also possible to distinguish between the diffusion and chemical reactions of dopants, as demonstrated for the cases of Cu in CdTe and Ag-doped HgCdTe.

I.Lyubomirsky, M.K.Rabinal, D.Cahen: Journal of Applied Physics, 1997, 81[10], 6684-91

Table 1

Diffusivity of Cu in CuInSe2

Table 2

Diffusivity of Ag, Cu and Li in CdTe