Durch intrinsische defekte induzierte uphill-diffusion von Ag und Cu in CdTe

In the framework of the present thesis, the diffusion of Ag in CdTe was investigated by the radiotracer $^{111}$Ag. Thereby the focus was on the possibility to create a Ag flux from regions of low Ag concentration to regions of high Ag concentration (uphill diffusion). The experimentally observed diffusion profiles are explained in the framework of a thermodynamic diffusion model, taking into account the defect charge state and the defect interaction. The distribution of the charged defects produces a electric field, which leads to a drift of the charged defects. The experimental data are well explained assuming that Ag is incorporated interstitially and ionized (Agi$^{+}$). The Agi$^{+}$ concentration then reflects the profile of the Fermi level, which again is determined by the intrinsic defect distribution or, more precisely, the deviation from stoichiometry. On the basis of the experimental data it is possible to gather information on the thermodynamic properties of extrinsic as well as intrinsic defects. Finally, it is shown that uphill diffusion takes place also in systems other than Ag in CdTe. It was observed also for the diffusion of Cu in CdTe, the diffusion of Ag in ZnTe and the codiffusion of two extrinsic defects (Ag and Cu as well as Ag and Au) in CdTe.