Bulk Zn 1-x Be x Te crystals were grown in the range extending up to x ¼ 0.12. Their structural, optical and photothermal properties were characterised using X-ray diffraction, photoluminescence (PL) and photoacoustic (PA) methods. The lattice constants are found to follow a linear dependence on x. Energy gap and thermal diffusivity were determined from photoacoustic spectra. The energy-gap increasing trend with rising beryllium content is in agreement with that reported for thin (Zn,Be)Te layers on InP substrate.Introduction Early theoretical studies [1,2] have shown that beryllium could be an attractive cationic substitution for ZnTe. A partial substitution of a cation (such as Zn or Cd) by Be improves the II-VI-based device properties because of highly covalent bonding and high cohesive energy in beryllium chalcogenides [3][4][5]. Therefore, it allows for the extension of structural and band-gap engineering of II-VI semiconductors towards lower lattice parameters and higher energy gaps. Beryllium is now applied as a component of II-VI heterostructures for blue light-emitting diodes, lasers and photodetectors. There is a number of papers on the properties of bulk and layered (Zn,Be)Se solid solution but relatively little information on tellurium based II-VI compounds with partial cationic substitution by Be atoms is available. Recent results show that Zn 1--x Be x Te is a promising material for p-type cladding layer of ZnCdSe/MgZnCdSe lasers on InP substrate [6]. (Zn,Be)(Te,Se) has been successfully applied in design of quantum wells [7]. ZnBeTe ternary alloy has been applied as a p-contact layer in II-VI lasers [8] and as a component of LEDs using an InP substrate [9]. High hole concentration (4.8 Â 10 18 cm --3 ) has been achieved in Zn 0.6 Be 0.4 Te layer (on InP substrate) exhibiting 2.97 eV band-gap energy [6]. As for the design of heterostructures the knowledge of bulk crystal properties is of fundamental importance, bulk ZnBeTe crystals have been grown and their properties are under investigation. Preliminary studies of luminescence and photoacoustic spectra of bulk Zn 1--x Be x Te crystals have been performed in [10] and [11], respectively. In this work, basic crystallographic, optical and thermal properties of bulk Zn 1--x Be x Te crystals grown by high pressure Bridgman method are reported.

Quaternary diluted magnetic semiconductor Zn 1--x--y Be x Mn y Se (0 < x < 0.25, 0 < y < 0.50) were grown by the Bridgman method. Raman scattering, photoluminescence and photoacoustic spectra were measured. The energy gap and thermal diffusivity values at room temperature were estimated from these measurements.

Optical and luminescence properties of the Bridgman‐grown Cd1–x –y Bex Zny Se and Zn1–x –y Bex Mgy Se crystals are reported. Spectroscopic ellipsometry was employed for determination of spectral dependence of the complex dielectric function $ \tilde \epsilon $(E) in the photon energy range 0.75–6.5 eV. Below the absorption edge the refractive indices n (E) of the alloys were modelled using a Sellmeier‐type relation. The excitonic band‐gap energies were estimated from the ellipsometric and photoluminescence measurements. Compositional effects in the ellipsometric and photoluminescence spectra are discussed. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Subject classification: 75.30.Et; 75.50.Pp; 76.30.Fc; S8.12 Magnetisation and EPR investigations were performed in mixed Zn 1--x--y Be x Mn y Se crystals. For crystals containing about 3% of Mn the transition from paramagnetic to antiferromagnetic behaviour is observed with temperature decreasing from 300 to 12 K. EPR spectra of all samples show the g-factor value in the range of 2.0065-2.0220. If Mn atoms are not introduced to the lattice, the EPR signal shows only g = 1.999.