Physica B 185 (1993) 245-249 North-Holland zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA PHYSICA 1 Centers of radiative and nonradiative recombination in isoelectronically doped ZnSe : Te crystals R. Baltramiejtinas”, V.D. Ryzhikovb, G. RaEiukaitis”, V. Gavryushin’, D. Juodibalis” and A. Kazlauskas’ zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA “Institute of Physics, Vilnius, Lithuania hlnstitute of Single Crystals, Kharkov, Ukraine ‘Department of Physics, Vilnius University, Lithuania Investigations of photoluminescence and of photo-induced absorption have been carried out on ZnSe and ZnSe:Te crystals. The parameters of deep levels and their connection with radiative properties of the crystals have been determined. The annealing of ZnSe:Te crystals in halogen vapor causes creation of IR-radiative centers of rapid hole capture which quench the red luminescence. 1. Introduction Crystals of ZnSe: Te are widely applied as scintillators for X- and y-radiation registration. High thermal and radiative stability of red luminescence of the crystals is the reason for such an application [l]. The influence of isoelec- tronic doping on the formation of radiative cen- ters is the aim of our investigation. The optical properties of ZnSe and ZnSe:Te annealed in vapors of the components have been investigated. The results enable us to separate some channels of red recombination. The nature of the centers is discussed. 2. Methods Stationary luminescence measurements were carried out at interband excitation of fresh-cut crystals by He-Cd cw-laser radiation (A = 4416 A, 0.1 W/cm*). A pulsed dye-laser was used to measure the excitation spectra of luminescence. Impurity absorption was con- ._ Correspondence to: R. BaltramieJunas, Institute of Physics, Vilnius 2600, Lithuania. trolled by a spectrophotometer ‘Specord M80’. The parameters and deep-level content were investigated by means of laser modulation of two-step absorption (LM TSA) via deep levels (DL), as discussed in detail in refs. [2,3]. A xenon pulse lamp with a continuous spectrum of radiation was used as a probe source of light. The absorption modulation was realized by a pulsed Nd-laser (fiti, = 1.17 eV, At = 50 ns). 3. Experiment Photoluminescence spectra of ZnSe : Te crys- tals are characterized by a complicated red- orange band which is an operating band for scintillators. Its structure changes from crystal to crystal, and it could be resolved partially at selective excitation (fig. 1). The annealing of the crystals in Zn promotes the formation of the R-band radiation (fig. 2(b)). The annealing in Te considerably decreases the luminescence in the red spectrum, while the annealing in Se totally quenches the R-band as well as BE-lines, and a near-edge DA-radiation decreases for about an order of magnitude. However, a new IR-band 0921-4526/93/$06.00 0 1993 - Elsevier Science Publishers B.V. All rights reserved