In the given paper, the temperature dependences ([Formula: see text]–300 K) of the green band intensity at wavelengths [Formula: see text] nm and [Formula: see text] nm have been measured and observed, respectively, from the polished and unpolished surface (PS and unPS) of a polycrystalline CVD (chemical vapor deposition) ZnSe sample upon excitation by X-ray quanta ([Formula: see text]. In both cases, the activation energy of thermal quenching has been determined, and the reasons for thermal quenching have been considered in detail. Along with XRL spectra analysis, the temperature behavior of the green band observed upon excitation by an ultraviolet (UV) laser (He–Cd, [Formula: see text] nm) from the PS and unPS in the temperature range [Formula: see text]–200 K has been discussed in more detail.
The photoluminescence spectra of CVD (chemical vapour deposition) ZnSe polycrystalline grown with a large excess of selenium and containing \O*Se-Cu+i\ complexes at stacking faults are studied. Absorbance was measured to complement these data. The features of the PL spectra in comparison with cathodoluminescence are considered. It is shown that PL bands identical to CL are observed as somewhat shorter wavelengths. For the studied crystals, a band model is presented according to the data obtained in this work. The low-energy shift of the PL spectra with decreasing excitation energy corresponds to a shift on the energy scale of the band model with a corresponding change in the type of radiative transitions. It is shown that identical photoluminescence bands are observed as somewhat shorter wavelengths than cathodoluminescence bands. For the crystals under study, a band model is presented according to the data obtained in the given decreasing work. The low-energy shift of the photoluminescence spectra upon the excitation energy corresponds to a shift along the energy scale of the band model with a corresponding change in the type of radiative transitions. Changes have been introduced that characterize the nature of the group of equidistant bands 477-490 nm, which are characteristic of ZnSe samples with an excess of oxygen and Se. The results can be useful for a more complete study of the structure of multiphonon exciton spectra of photo and cathodoluminescence of AIIBVI crystals. Keywords: band model, narrow-line multi-photon spectra, exciton radiation, stacking faults, isoelectronic oxygen impurity, carrying effective negative charge.
We present the photoluminescence spectra obtained in the case of normal incidence of exciting radiation at both polished and unpolished surfaces of chemicalvapour deposited ZnSe films in the temperature range 12-300 K. The luminescence has been excited using either a continuous-wave He-Cd laser with the wavelength λ ex = 325 nm (i.e., under the condition hv ex > E g for the photon energy) or a semiconductor laser with λ ex = 532 nm (i.e., hv ex < E g). We show that the temperature dependences of intensity, spectral position and half-width of a green photoluminescence band detected in the both alternative cases are very different in the region 12-80 K. However, their behaviours become very close to each other when the temperature increases up to 180 K. Finally, the above spectral parameters are almost the same in the region 180-300 K.
Diluted magnetic semiconductors (DMSs) are known as semi-magnetic compounds in which a managed fraction of nonmagnetic cations are replaced by 3d transition metals (TMs). TM 2þ magnetic ions doped II-VI semiconductor compounds are counted as promising optoelectronic materials in the mid-IR region, low energy optical phonon cut-off, and large emission cross-sections. [1,2] The development of Zn-based DMSs II-VI group shows magnificent properties, which have a huge opportunity to be applied in spintronics. [3][4][5][6] These materials have attracted a lot of attention as materials for spintronic applications [7][8][9][10][11][12] because of their half-metallic ferromagnetic (HMFM) behaviors at Curie temperatures higher than room temperature. [13][14][15] These properties were observed in V-, Cr-, and Mn-doped ZnO and ZnTe [16] also in V-, Cr-, and Fe-doped CdTe, [17][18][19] in Cd-and Mn-doped CdS, [20][21][22] and Mn-doped GaAs. [23] In refs. [24][25][26][27][28][29][30][31][32], it was reported that Cr impurities in II-VI semiconductors make FM materials at room temperature.Zinc selenide, a semiconductor, can operate as a half-metallic compound and is a helpful material for optoelectronic and spintronic applications. Zinc selenide is a nonmagnetic material with a direct bandgap of 2.70 eV and has great potential for a diversity of optical and electro-optical devices, such as short wavelength lasers, blue-green laser diodes, pure green lightemitting diodes, microwave and terahertz devices, solar cells and tunable mid-IR laser sources. [33][34][35] TM-doped ZnSe has attracted great research interest as new productive device applicants. , the authors reported that ZnSe:TM was appropriate for applications in spintronics and middle-IR lasing. Sato et al. [26] have predicted high Curie temperatures for Cr-and V-doped zincblende ZnSe, Benstaali et al. [35] in ZnSe:Co, Mohamood et al. [42] in ZnSe:Ti, and Arifet et al. [43] in CdSe:Co reported half-metallic FM due to polarization of the spin in their theoretical study and suggested these are potential candidates for spintronic application, which are in agreement with current work.This work is dedicated to the study of the magnetism in ZnSe: Co and ZnSe:Ni by varying the impurity concentrations for the values x ¼ 12.5% and 6.25%. In the current work, the Curie temperatures are also estimated and obtained that Ni-doped ZnSe compounds are high room temperature materials.The same properties were predicted in current work for TM: ZnSe in the FM and antiferromagnetic (AFM) phases and may be suited as a reference for the FM II-VI DMSs in their alloys and heterostructures.
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