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Determination of trap density in CdSe thin films from thermally stimulated conductivity spectra

Z. ANEVA1,* , D. NESHEVA1, C. MAIN2, S. REYNOLDS3,4

Affiliation

  1. Institute of Solid State Physics, Bulgarian Academy of Sciences, 72 Tzarigradsko Chaussee Blvd., 1784 Sofia, Bulgaria
  2. University of Dundee, Division of Electronic Engineering and Physics, Dundee DD1 4HN, UK
  3. bUniversity of Dundee, Division of Electronic Engineering and Physics, Dundee DD1 4HN, UK
  4. Institut für Photovoltaik, Forschungszentrum Jülich GmbH, D-52425 Jülich, Germany

Abstract

The trap density Nt and mobility-lifetime product μτ in CdSe thin films are investigated combining data from thermally stimulated conductivity and photoconductivity measurements. A method of simultaneous fitting of thermally stimulated conductivity spectra is applied and four peaks at 193, 213, 230 and 258 K are resolved in the temperature range 80-270 K. Temperature dependences of the steady-state photoconductivity under excitation with strongly absorbed light (525 and 630 nm) are measured at photon fluxes of 5x1013 - 5x1015 cm-2.s-1 and temperature dependences of the exponent γ in the intensity dependence of the photoconductivity are obtained. The μτ products and trap densities Nt are calculated for both kinds of light excitation. It is shown that they depend on the wavelength of the exciting light, being 2-3 times larger for excitation with λ=630 nm..

Keywords

CdSe thin films, Thermally stimulated conductivity, Density of states.

Submitted at: Nov. 1, 2006
Accepted at: Jan. 15, 2007

Citation

Z. ANEVA, D. NESHEVA, C. MAIN, S. REYNOLDS, Determination of trap density in CdSe thin films from thermally stimulated conductivity spectra, Journal of Optoelectronics and Advanced Materials Vol. 9, Iss. 1, pp. 205-208 (2007)