Optical characterization of bulk Zn_1−xBe_xTe crystals

Abstract

This paper presents an optical characterization of three bulk sphalerite Zn 1−x Be x Te crystals grown by the modified high pressure Bridgman method. The study was conducted in the near-band-edge interband transition regime using low temperature photoluminescence (PL), temperature-dependent contactless electroreflectance (CER) and/or photoreflectance (PR) in the temperature range of 15-400 K, and surface photovoltage spectroscopy (SPS) at room temperature. PL spectra at low temperatures of the samples investigated consist of an excitonic line, a band due to recombination of free electrons with holes located at shallow acceptors and a broad band related to recombination through deeper level defects. The band-edge excitonic transitions have been observed in the CER/PR spectra. The fundamental transition energies E 0 are determined via lineshape fits to the CER/PR spectra. The values of E 0 at room temperature obtained from CER/PR spectra correspond well to that determined from SPS measurements, and the Be contents x of the samples are determined using a linear equation which describes the room temperature band gap dependence on composition for the Zn 1−x Be x Te alloy system. The parameters describing the temperature dependence of the band-edge excitonic transition energies are evaluated and discussed.

First-principles calculations of the structural, electronic, elastic, phase diagram and thermal properties of Zn1−xBexTe ternary alloy

“…Some experimental studies on the basic properties of this compound are available in the literature [3][4][5][6]. In particular, little is known about the optical and photoluminescence properties of bulk Zn 1−x Be x Te solid solutions [6], and their dielectric functions in a spectral range from far infrared to ultraviolet have not yet been reported. On the theoretical side [7,8], during the last few years, few attempts have been made at predicting their physical properties.…”