Optical characterization ofZn0.95−xBexMn0.05Semixed crystals

Abstract

A systematic study of a series of Zn 0.95−x Be x Mn 0.05 Se mixed crystals with different Be content ͑0.05Յ X Յ 0.20͒ grown by the modified high-pressure Bridgman method were carried out by room-temperature surface photovoltage spectroscopy ͑SPS͒, temperature-dependent photoluminescence ͑PL͒, and contactless electroreflectance ͑CER͒. A typical PL spectrum at low temperature consists of free exciton line, an edge emission due to recombination of shallow donor-acceptor pairs, and the Mn 2+ -related intraionic emission. The near bandedge transition energies determined by analyzing the CER and SPS spectra showed a blueshift with the increase in Be content. The peak positions of band-edge exciton features in the PL spectra shifted slightly toward lower energies as compared to the corresponding transition energies obtained from CER and SPS data. The observed increases in the CER-PL shift with the increasing of Be content are explained by the increasing compositional disorder causing the smearing of the band-edge energies. The excitonic line broadening for the samples with larger Be/Zn ratio are attributed in part to the alloy-scattering effects and also to the poorer crystalline quality of the samples with higher content of Be. In addition, the parameters that describe the temperature dependence of the transition energies and broadening parameters of the band-edge excitonic transitions were evaluated and discussed.

Phase formations and tunable red luminescence of Na2CaMg1−xMnx(PO4)2 (x = 0.05–1.0)

“…An emission shift could occur by controlling surrounding environments of optically active ions doped in hosts such as semiconductors 27 and dielectric material. 28 The control of emission shift leads to the ability to tune a color point of the phosphor.…”

EXAFS studies of novel impulsive hardening in the Be–Zn–Se semiconductor alloys

“…5 In-spite of the readiness of the ZnSe for the device deployability, its device life-times are typically small. 6 Hence, most of the recent research efforts are focused on the aspect of materials engineering to improve the quality of the ZnSe. Rapid propagation of lattice defects and their duplication are mainly responsible for the gradual degradation of physical character of the ZnSe and thus reduction in the devices' life times.…”

“…Although it is not easy to introduce the covalent character in the ionic ZnSe, the covalence related hardness in the lattice is accomplished by pairing the Se atom with the Group-I atom like Be through the substitutional doping. 6,7 On the contrary, the substitutional addition of Be also promotes a high bond length contrast that consecutively induces some novel structural properties in the resulting Be x Zn 1−x Se solid solution. 8,9 It is important to note that the bond lengths of bulk zinc selenide (∼2.45Å) and bulk beryllium selenide (∼2.1Å) differ by ∼17%; the Be-Se bond is shorter and stiffer than the Zn-Se bond.…”

Ambient Zinc K-Edge Extended X-Ray Absorption Fine Structure Studies on Solid Solution Hardening of the Ternary Alloys

“…Other noticeable difficulties in the ZnSe lasing devices instigate from iconicity-induced so-ening of the lattice. A renewed interest in mixed ZnSebased systems arises aer several recent ab initio quantum calculations and experimental studies [7,8] which predict large covalent bonding between dopant atoms of beryllium and chalcogenide atoms of the mixed crystal and subsequent reduction in overall bond distances, which is a unique observance among the highly ionic II-VI semiconductors. For this reason, the Zn 1 Be Se alloys are a new class of II-VI ternary semiconducting compounds that are formed from the binaries with highly contrasting bond-length properties [7].…”