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Study of generation-recombination processes of non equilibrium charge carriers in single crystalline thin GaSe(Cu) films

E. CUCULESCU1, Ig. EVTODIEV1, M. CARAMAN2, L. LEONTIE3,*

Affiliation

  1. Kishinev State University, 60 A Mateevici Str., Kishinev, MD-2009, Republic of Moldova
  2. Bacau University, 157 Calea Marasesti, 600115 Bacau, Romania
  3. “Al.I. Cuza” University, 11 Carol I Bd., 700506 Iasi, Romania

Abstract

The generation-recombination processes of non-equilibrium charge carriers in undoped and Cu-doped (in the range 0.1-0.5 at.%.) single crysta line GaSe films with thickness d in the range 1.5-225 µm are investigated. Cu doping of GaSe crystals up to 0.5 at.% leads to an increase of electrical conductivity by over 4 orders of magnitude, as we l to enhancement of impurity luminescence band (PL) and extension of photoconductivity spectral range. By studying PL and photonductivity spectra, for different excitation (photon) energies in temperature range (78-420) K, energies of localized states due to both Cu and accidental impurities are determined. By analysing temperature dependence of electrical conductivity and photoconductivity for undoped and Cu-doped films, the activation energy of acceptor levels in doped films was determined as 0.058 and 0.025 eV. Increasing Cu doping from 0.1 to 0.5 at.%. results in decreasing energy of acceptor levels up to ∼0.02 eV. By analysing the impurity absorption and photoconduction at 78 K the energy of acceptor levels was determined as 12-15 meV greater than previously evaluated, depending on Cu concentration. For films with d<5 µm, the surface states concentration increased for Cu doping over 0.3 at.%..

Keywords

GaSe(Cu), Thin films, Photoluminescence, Photoconduction.

Submitted at: Oct. 14, 2005
Accepted at: Jan. 26, 2006

Citation

E. CUCULESCU, Ig. EVTODIEV, M. CARAMAN, L. LEONTIE, Study of generation-recombination processes of non equilibrium charge carriers in single crystalline thin GaSe(Cu) films, Journal of Optoelectronics and Advanced Materials Vol. 8, Iss. 1, pp. 112-118 (2006)