Y C Shih et al 2008 J. Phys.: Condens. Matter 20 255227 doi:10.1088/0953-8984/20/25/255227
Y C Shih1, Y S Huang1,4, F Firszt2, S Łęgowski2, H Męczyńska2 and K K Tiong3
Show affiliationsThis paper presents an optical characterization of three bulk sphalerite Zn1−xBexTe 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 E0 are determined via lineshape fits to the CER/PR spectra. The values of E0 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 Zn1−xBexTe alloy system. The parameters describing the temperature dependence of the band-edge excitonic transition energies are evaluated and discussed.
71.20.Nr Semiconductor compounds
81.10.Fq Growth from melts; zone melting and refining
Issue 25 (25 June 2008)
Received 21 February 2008, in final form 26 March 2008
Published 22 May 2008
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