Dresden 2006 – scientific programme

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HL: Halbleiterphysik

HL 35: II-VI semiconductors III

HL 35.6: Talk

Wednesday, March 29, 2006, 15:45–16:00, POT 151

Internal Drift Effects on the Diffusion of Ag in CdTe — •H. Wolf¹, F. Wagner¹, Th. Wichert¹, and ISOLDE collaboration² — ¹Technische Physik, Universität des Saarlandes, D-66041 Saarbrücken, Germany — ²CERN, DH-1211 Geneva 23, Switzerland

Unusual concentration profiles have been observed upon diffusion of Ag in CdTe [1]. The diffusion experiments were performed with the radiotracers ¹¹¹Ag implanted into one side of a typically 800 µm thick CdTe crystal at a depth of about 30 nm. The resulting diffusion profiles of Ag extending over the whole crystal critically depend on the respective external conditions during diffusion and on the sample pre-treatments. After diffusing the Ag dopant into the CdTe crystal at 800 K (60 min) under vacuum or Cd pressure the symmetrical concentration profiles show depletion layers of 100 or 300 µm below the surfaces of the crystal, whereby the depletion layers are much stronger pronounced in case of diffusion under Cd pressure. In contrast, the Ag concentration is increased at the surface and decreased in the interior of the crystal if the diffusion is performed under Te pressure. The Ag profiles are well described within a model based on an interaction of the dopant Ag atoms with the intrinsic defects of the Cd sublattice of CdTe taking into account the charge states of all participating defects. The diffusion of Ag is significantly affected by an internal drift due to the electric field generated by the distribution of the charged defects.
supported by the BMBF, contracts 05KK1TSB/7 and CZE 03/002.
H. Wolf, F. Wagner, Th. Wichert, and ISOLDE Collaboration, Phys. Rev. Lett. 94, 125901, 2005.