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Thermally-stimulated currents in thin-film semiconduc-tors – computer modelling and experiment

C. MAIN1,* , Z. ANEVA2, S. REYNOLDS1, N. SOUFFI3, D. NESHEVA2, R. BRUGGEMANN3

Affiliation

  1. University of Dundee, Division of Electronic Engineering and Physics, Dundee,DD1 4HN, UK.
  2. Institute of Solid State Physics, Bulgarian Academy of Sciences, 72 Tzarigradsko Chaussee Blvd., 1784 Sofia, Bulgaria
  3. Carl von Ossietzky Universitat, Fachbereich Physik, D26111, Oldenburg, Germany

Abstract

We apply computer modelling to the multiple-trapping rate equations governing the time-evolution of non-equilibrium distributions of electrons and holes in extended and localised states in thin-film semiconductors, in thermally-stimulated conductivity measurements. We examine in detail the application of this method as a ‘spectroscopy’ of the energy distribution of localised states. Factors influencing energy and density scales are examined critically. Such factors include whether ‘weak’ or ‘strong’ re-trapping prevails during the measurement; the use of non-physical ‘effective’ attempt-to-escape frequencies; the effect of lifetime variation as distributions relax, and whether this can be measured accurately by supplemental steady-state photoconductivity. We show that in some circumstances, the energy scale can be approximated by the quasi-Fermi level position, and suggest further that the density of states may then be computed using the derivative of the quasi-Fermi energy with respect to temperature..

Keywords

Thin films, Electrical properties, Computer simulation, Thermally stimulated currents.

Submitted at: Nov. 28, 2006
Accepted at: Jan. 15, 2007

Citation

C. MAIN, Z. ANEVA, S. REYNOLDS, N. SOUFFI, D. NESHEVA, R. BRUGGEMANN, Thermally-stimulated currents in thin-film semiconduc-tors – computer modelling and experiment, Journal of Optoelectronics and Advanced Materials Vol. 9, Iss. 1, pp. 114-120 (2007)