ISSN:
1089-7550
Source:
AIP Digital Archive
Topics:
Physics
Notes:
A center in plastically deformed CdS, labeled herein as the SDX center, was investigated by means of deep level transient spectroscopy, thermally stimulated capacitance, photocapacitance, and Hall effect measurements. The essential features of the center are: thermally activated electron capture with an activation energy (0.30 eV), comparable with the electron emission activation energy (0.40 eV); an optical ionization energy of the SDX center (1.47 eV) significantly exceeding the equilibrium electron binding energy (0.1 eV); a persistent photoconductivity at low temperatures; dependence of electron emission from SDX centers in an electric field is significantly weaker than expected from the Pool–Frenkel effect. The concentration of SDX centers, as measured by methods of capacitance spectroscopy and conductivity, increases with increasing density of screw dislocations. Exponential electron thermo-emission from the SDX center is accompanied by nonexponentiality of the electron capture. The capture kinetics is fitted using several models. The best agreement with the data is obtained for the model of randomly distributed barrier heights. A model of the origin of SDX centers is proposed and discussed. According to the model, SDX center is a noneffective-mass state (DX level) of a shallow substitutional donor (possibly Al). In as-grown samples, it cannot be occupied because it lies significantly above the Fermi level. In plastically deformed samples the DX level moves down to the Fermi level under the elastic lattice distortions around dislocations and becomes detectable. © 1996 American Institute of Physics.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.363400
