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61.
以化合物Zn(NH4)3Cl5为气相输运剂,ZnSe多晶为原料,用化学气相输运技术(CVT)在封闭石英管中生长出直径9 m m、长度25 mm的Zn1+0 031Se单晶晶体生长区的温度为898~915℃,温度梯度为1.5℃@cm-1,生长周期为21 d.晶体生长端由{111}和{100}单形包围.用RO-XRD技术研究了晶体的结晶质量,ZnSe(111)的RO-XRD谱的FWHM为24 s.光致发光特性研究表明,Zn1+0.031Se单晶体的PL谱由Fx(439 nm)和BBT(418 nm)等发光峰组成,晶体的短波吸收限位于465 nm处,腐蚀点密度为(5~7)×104cm-2.化合物Zn(NH4)3Cl5具有较高的热稳定性,是一种适合气相生长ZnSe单晶的新型输运剂. 相似文献
62.
B. C. Karrer F. C. Peiris Brenda Vanmil Ming Luo N. C. Giles Thomas H. Myers 《Journal of Electronic Materials》2005,34(6):944-948
We have determined the optical properties of a series of Cl-doped ZnSe epilayers grown on GaAs substrates using ellipsometry
and prism coupling. Initially, the carrier concentrations were determined using Hall measurements for samples between 6.30×1016 cm−3 and 9.50×1018 cm−3. Using a variable angle spectroscopic ellipsometer in the energy range between 0.7 eV and 6.5 eV, we then obtained experimental
spectra for each of the samples. By incorporating a three-layer model to simulate the experimental data, we determined the
complex dielectric functions for these Cl-doped ZnSe epilayers. In order to facilitate this modeling procedure, we have complemented
the ellipsometric results with prism coupling experiments that measured the film thickness and the index of refraction (at
discrete wavelengths) very precisely. For the fundamental band gap, we observe a blue shift with respect to the doping concentration,
which can be explained by the Burstein-Moss effect. In addition, we have determined the critical point parameters related
to these specimens by fitting the second derivatives of both the real and the imaginary parts of the dielectric functions.
Similar to several doped III-V semiconductors reported thus far, we find that in Cl-doped ZnSe epilayers, both E1 and E1 + Δ
1 red shift, as well as a broadening with respect to the doping concentration. 相似文献
63.
S. K. Chan N. Liu Y. Cai N. Wang G. K. L. Wong I. K. Sou 《Journal of Electronic Materials》2006,35(6):1246-1250
Molecular beam epitaxy (MBE) via the vapor-liquid-solid (VLS) reaction was used to grow ZnSe nanowires (NWs) on (111), (100),
and (110) oriented GaAs substrates. Through detailed transmission electron microscopy (TEM) studies, it was found that 〈111〉
orientation is the growth direction for NWs with size ≥30 nm, while NWs with size around 10 nm prefer to grow along the 〈110〉
direction, with a small portion along the 〈112〉 direction. These observations have led to the realization of vertical ZnSe
NWs with size around 10 nm grown on a GaAs (110) substrate. An ordered ZnSe NW array fabricated on a GaAs (111) substrate
with a novel prepatterning method associated with plasma etching shows a high degree of ordering and a good size uniformity
of the as-grown NWs. The diameter of the NWs in the array is around 80 nm and most of them are found to orient vertically,
but some tilt to one of the six possible directions of the 〈111〉 family. 相似文献
64.
J.J. Andrade A.G. Brasil Jr. P.M.A. Farias A. Fontes B.S. Santos 《Microelectronics Journal》2009,40(3):641-643
In this work we show a new experimental methodology to obtain ZnSe nanocrystals in aqueous solution aiming their application as biophotonic probes. The nanocrystals were obtained using a simple procedure based on the arrested precipitation of ZnSe in aqueous solution in the presence of a thiol-alkyl stabilizing agent, in air and at room temperature. Using post-preparative experimental procedures on the colloidal particles, blue and green emissions were observed. The structural characterization (powder X-ray diffraction and electronic transmission microscopy) shows that the particles were obtained in the quantum confinement regime (d=2-4 nm) and possess a zinc-blend crystalline structure. The optical properties of the suspensions were determined by electronic absorption, excitation and emission spectroscopies and are discussed in terms of their size and chemical compositions. 相似文献
65.
Wei Chen Xiaojie Li Fei Wang Shaghraf Javaid Yingping Pang Jiayi Chen Zongyou Yin Shaobin Wang Yunguo Li Guohua Jia 《Small (Weinheim an der Bergstrasse, Germany)》2020,16(12)
For the first time, colloidal gold (Au)–ZnSe hybrid nanorods (NRs) with controlled size and location of Au domains are synthesized and used for hydrogen production by photocatalytic water splitting. Au tips are found to grow on the apices of ZnSe NRs nonepitaxially to form an interface with no preference of orientation between Au(111) and ZnSe(001). Density functional theory calculations reveal that the Au tips on ZnSe hybrid NRs gain enhanced adsorption of H compared to pristine Au, which favors the hydrogen evolution reaction. Photocatalytic tests reveal that the Au tips on ZnSe NRs effectively enhance the photocatalytic performance in hydrogen generation, in which the single Au‐tipped ZnSe hybrid NRs show the highest photocatalytic hydrogen production rate of 437.8 µmol h?1 g?1 in comparison with a rate of 51.5 µmol h?1 g?1 for pristine ZnSe NRs. An apparent quantum efficiency of 1.3% for hydrogen evolution reaction for single Au‐tipped ZnSe hybrid NRs is obtained, showing the potential application of this type of cadmium (Cd)‐free metal–semiconductor hybrid nanoparticles (NPs) in solar hydrogen production. This work opens an avenue toward Cd‐free hybrid NP‐based photocatalysis for clean fuel production. 相似文献
66.
Devki N. Talwar Tzuen-Rong Yang Wu-Ching Chou 《Science and Technology of Advanced Materials》2016,17(1):777-791
A comprehensive lattice dynamical study is reported to emphasize the vibrational behavior of perfect/imperfect zinc-blende (zb) ZnSe, MnSe and Zn1?xMnxSe alloys. Low temperature far-infrared (FIR) reflectivity measurements performed on a series of molecular beam epitaxy grown Zn1?xMnxSe/GaAs (001) epilayers have a typical ‘intermediate-phonon-mode’ behavior. Besides perceiving ZnSe- and MnSe-like TO-phonon resonances, the study also revealed a weak Mn alloy-disorder mode below MnSe band. A classical effective-medium theory of multilayer optics is used to evaluate dielectric tensors of both epilayers and substrate for simulating reflectivity and transmission spectra of ultrathin epifilms and superlattices at near normal and/or oblique incidence. In the framework of a realistic rigid-ion model and exploiting an average t-matrix Greens function (ATM-GF) theory we appraised the vibrational properties of nitrogen and phosphorous doped Zn-Mn chalcogenides. Lattice relaxations around isolated NSe (PSe) defects in ZnSe and zb MnSe are evaluated by first principles bond-orbital model that helped construct perturbation models for simulating the localized vibrational modes (LVMs). Calculated shift of impurity modes for isotopic 14NSe (15NSe) defects in ZnSe offered a strong revelation of an inflexible defect–host interaction. By retaining force constant change parameter of 14NSe (15NSe) in heavily N-doped ZnSe, the ATM-GF theory predicted (a) three non-degenerate LVMs for the photoluminescence defect center VSe-Zn-14NSe (VSe-Zn-15NSe) of Cs symmetry, and (b) six impurity modes for the second nearest-neighbor NSe-Zn-NSe pair defect of C2v symmetry. From the range of simulated defect modes, we have ruled out the possibility of N-pairs and justified the presence of VSe-Zn-NSe complex centers – likely to be responsible for the observed large absorption bandwidth in highly N-doped ZnSe. High resolution measurements of FIR absorption and/or Raman scattering spectroscopy are needed to validate the accuracy of our theoretical conjectures. 相似文献
67.
68.
J. Ren Y. Lansari Z. Yu J. W. Cook J. F. Schetzina 《Journal of Electronic Materials》1993,22(8):973-975
Integrated heterostructure devices which combine small band gap and large band gap II–VI materials in multilayered structures
for light emission and detection applications are described. 相似文献
69.
We present a semi-empirical sp3s? tight binding model to calculate the effects of alloy composition and strain on electronic band structure of Cd and Zn based group II-VI heterostructures for photovoltaic devices. The semi-empirical sp3s? TB model Hamiltonian includes second nearest neighbor interactions and spin-orbit splitting of p-states. Bond lengths and atomic energies of cation and anion forming ternary semiconductors are taken as nonlinear function of composition. The 2NN sp3s? tight binding model calculations are compared with those of the package program WIEN2k which uses the generalized gradient approximation (GGA) and local spin density approximation (LSDA) based scaling law for the scissor operator for the self energy corrections to the DFT energy band gaps of semiconductors. We found that both the GGA and LSDA corrected WIEN 2k simulations and 2NN sp3s? TB model accurately reproduces the band gaps and both the valence band and conduction band dispersion curves at Γ, X and L high symmetry points of Brillouin zone, also in good agreement with experiment. 相似文献
70.
B. L. Vanmil A. J. Ptak L. Bai Lijun Wang M. Chirila N. C. Giles T. H. Myers Larry Wang 《Journal of Electronic Materials》2002,31(7):770-775
Epitaxial ZnSe layers were grown by molecular beam epitaxy (MBE) to study Cr incorporation with the long-term goal of demonstrating
an alternate route for achieving transition-metal-doped lasers. Concentrations between 1015 atoms cm−3 and 4×1020 atoms cm−3 were achieved. Secondary ion-mass spectroscopy (SIMS) concentration profiles strongly suggest that surface segregation and
accumulation of Cr occurs during growth. Photoluminescence (PL) measurements indicate Cr is incorporated in the optically
active Cr2+ state up to levels of ∼1019 cm−3. Electron paramagnetic resonance (EPR) studies suggest that the Cr atoms exhibit collective magnetic behavior even at these
levels. X-ray diffraction (XRD) and reflection high-energy electron diffraction (RHEED) indicate high structural quality is
maintained for Cr incorporation for levels up to ∼1019 atoms cm−3. 相似文献