Deep center luminescence in p-type CdTe

Abstract

The deep-level photoluminescence (PL) emission in the 1.1 eV spectral region in p-type CdTe:Cl polycrystalline samples was studied as a function of the excitation laser power and temperature. The relatively broad 1.1 eV PL band has a nonsymmetrical shape which can be easily changed by varying the excitation laser power. Detailed analysis of the line shape shows that the 1.1 eV emission contains two distinct separate bands. These two bands have their zero-phonon peaks located at 1.08 and 1.17 eV, respectively, and they have quite different half-widths. A donor–acceptor (DA) pair model with a deep donor and a deep acceptor with ED and EA both ≳0.5 eV is proposed to explain the observed experimental findings. In this model the 1.08 and 1.17 eV bands are formed as a DA recombination between pairs of the nearest neighbors, and between pairs of the next-nearest neighbors, respectively. It is concluded that the acceptor in these pairs must be an interstitial atom. One possible realization for this kind of a DA pair is the VTe–Tei complex, where VTe is acting as a donor and Tei as an acceptor.