Influence of Au diffusion on structural, electrical and optical characteristics of CdTe thin films


Dzhafarov T. D. , Caliskan M.

JOURNAL OF PHYSICS D-APPLIED PHYSICS, cilt.40, ss.4003-4009, 2007 (SCI İndekslerine Giren Dergi) identifier identifier

  • Cilt numarası: 40 Konu: 13
  • Basım Tarihi: 2007
  • Doi Numarası: 10.1088/0022-3727/40/13/014
  • Dergi Adı: JOURNAL OF PHYSICS D-APPLIED PHYSICS
  • Sayfa Sayıları: ss.4003-4009

Özet

Diffusion of Au and its effects on structural, electrical and optical properties of CdTe films fabricated by the close-spaced sublimation technique have been investigated. Diffusion of Au was studied in the range 400-550 degrees C using energy dispersive x-ray fluorescence analysis. Au-doped and un-doped CdTe films were characterized by x-ray diffraction (XRD), electrical and optical absorption measurements. The temperature dependence of the diffusion coefficient of Au in CdTe films is described as D = 4.4 x 10(-7) exp(-0.54 eV/kT). The mechanism of Au diffusion in polycrystalline CdTe films is attributed to the fast migration of Au along grain boundaries with simultaneous penetration into grains and settling on Cd-vacancies. It is supposed that the weak influence of Au diffusion on XRD patterns of CdTe films can be explained by dispersal of Au atoms preferentially on Cd-vacancies owing to proximity of the covalent radius of Au and Cd. Au atoms, placed on Cd-vacancies (AuCd) during fast cooling from diffusion temperature to room temperature, show an acceptor behaviour with an energy level about of E-v + 0.2 eV. The nature of this level is discussed.