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.

Cathodoluminescence investigations on CdTe and Cd0.96Zn0.04Te crystals

“…In the low-energy region below 1.4 eV, both the CdTe and Cd 0.96 Zn 0.04 Te crystals give a weak broad emission consisting of two emission bands at 1.09 and 1.02 eV, similar to earlier observations by Krustok et al [3]. The energy positions of these emission bands do not vary much with increasing temperature and neither do their characteristics show any appreciable difference between CdTe and Cd 0.96 Zn 0.04 Te.…”

“…2 and 4). This broad emission that occurs in the spectral range 1.2-1.5 eV in CdTe is generally called defect band in the literature (and detrimental for devices application), and the peak positions differ widely among different samples depending on the crystal growth and sample preparation conditions [3,5,8,[13][14][15]. As can be seen in Fig.…”

Photoluminescence study of the 1.3–1.55eV defect band in CdTe

“…There is a sharp change in peak intensities around 68 K. Also, a smaller change is observed at around 36 K. We tentatively associate this with an increase in nonradiative recombination resulting from thermal activation of two unknown traps. Similar behavior was observed by Krustok et al [15].…”

Fundamental Research on Infrared Detection

“…The two high energy peaks had no noticeable phonon replicas, meaning that no lattice distortion is present. As the temperature increases, the peak area rapidly decreases around 68 K, and around 36 K. We associate a decrease in PL with an increase in non-radiative combination due to thermal activation of two unknown traps [7].…”