Photoluminescence (PL) measurements of (x \ 0.5) single CuIn 1~x Ga x Se 2 crystals grown by the vertical Bridgmann technique were made at temperatures ranging from 11 K to 200 K and with various excitation powers. At low temperatures only one asymmetric PL band (BT-band) is present at 1.23 eV. It has a steeper decline on the high-energy side and nearly temperature independent low-energy side. At higher temperatures (T [ 140 K) the BB-band becomes visible at 1.31 eV. We used an asymmetric double sigmoidal function to Ðt the experimental PL spectra. The results of this Ðtting can be interpreted to show the presence of spatial potential Ñuctuations in our samples. Observed dependencies would seem to reveal that the BT band is indeed connected with the recombination of a free electron with a localized hole. It is shown that these relatively deep localized states are probably formed due to potential Ñuctuations in highly compensated material and are not connected with any particular acceptor defect. We show that this model conforms to most of the discovered dependencies.
Pronounced Purcell enhancement of spontaneous emission in CdTe/ZnTe quantum dots embedded in micropillar cavities Appl. Phys. Lett. 101, 132105 (2012) Effects of Co content on the structural, luminescence, and ferromagnetic properties of Zn1−xCoxSy films J. Appl. Phys. 112, 063712 (2012) Mechanisms of infrared photoluminescence in HgTe/HgCdTe superlattice J. Appl. Phys. 112, 063512 (2012) Leaky mode analysis of luminescent thin films: The case of ZnO on sapphire J. Appl. Phys. 112, 063112 (2012) Observation of In-related collective spontaneous emission (superfluorescence) in Cd0.8Zn0.Several experimental photoluminescence ͑PL͒ bands of different energies for variously prepared CdTe samples are compared. Temperature variation of the PL intensity is modeled with two nonradiative thermal activation energies, of which E T1 is dominant for about Tр60 K, and E T2 for the upper temperature range of the measurement. The size of E T1 is invariably of the order of a few meV and, although of unclear origin, its magnitude is usually interpreted as an electronic energy level difference over which the carriers escape by thermal excitation. In CdTe the existence of such a small energy level difference E T1 is not easy to explain. On the contrary, we find clear evidence that, at low temperature, the PL intensity reduction with increasing temperature in fact results from the approximately T Ϫ2 temperature dependent capture cross sections of the carriers at the recombination centers, and not from a genuine thermal activation energy E T1 .
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.
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