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161.
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163.
ZnSe薄膜的激子光谱 总被引:5,自引:2,他引:3
采用分子束外延 (MBE)技术 ,在 Ga As(1 0 0 )衬底上生长了厚度从 0 .0 4 5到 1 .4μm的 Zn Se薄膜 .X射线衍射谱证实 ,随着薄膜厚度的增加 ,应变逐步弛豫 .测量了低温下样品的反射谱和光致发光谱 ,观察到轻重空穴的能级在不同应变下的分裂、移动和反转 ,以及激子极化激元 (Po-lariton)对反射谱的影响 .也观察到束缚激子发光随着薄膜厚度的变化规律 :束缚在中性受主杂质上的束缚激子发光 (I1峰 )随着薄膜厚度的增加逐渐变弱直至消失 ,而束缚在中性施主杂质上的束缚激子发光 (I2 峰 )则随着厚度增加逐渐增强 . 相似文献
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165.
研制了石英质射频激励等离子体活性氮源 ,将此氮源安装到国产 FW- 型分子束外延设备上 ,成功地生长了 p型 Zn Se:N优质单晶薄膜 .SIMS测量表明 ,薄膜中氮浓度高达~ 1.5× 10 2 0 cm- 3;PL 测量表明 ,氮在 Zn Se中形成了受主能级 ;C- V测量表明 ,净空穴浓度 [Na]- [Nd]≈ 5× 10 1 7cm- 3,达到了制备原理性蓝绿色激光二极管的要求 (~ 4.0× 10 1 7cm- 3) .C- V测量的结果同时得到远红外光谱法测量数据的佐证 . 相似文献
166.
Using the variational method and the effective mass and parabolic band approximations, electron and heavy-hole ground-state energies and exciton and photoluminescence energies are calculated in ultra-thin quantum wells of CdTe/ZnTe heterostructures. The results indicate dependencies on the well width, the barrier height, and stress-related effects and occur because the wave functions of both free carriers and those bound in exciton form determine the system energy and are shaped by the geometry of the well. Critical system thicknesses were estimated for the point at which stress effects become negligible: a value of five monolayers was obtained based on the exciton binding energy, and a value of seven monolayers was obtained based on the free-carrier ground-state energy. 相似文献
167.
A.P. Pardo Gonzalez H.G. Castro-LoraL.D. López-Carreño H.M. MartínezN.J. Torres Salcedo 《Journal of Physics and Chemistry of Solids》2014
ZnSe thin films were deposited onto Corning glass and silicon substrates using thermal evaporation. The samples were prepared at different substrate temperatures. The thin films’ surface chemical composition was determined through Auger electron spectroscopy (AES). AES signals corresponding to Zn and Se were only detected in AES spectra. The samples’ crystallographic structure was studied through X-ray diffraction. The material crystallised in the cubic structure with preferential orientation (111). Optical properties of the ZnSe films were studied over two energy ranges via electron energy loss spectroscopy (10–90 eV) and spectral transmittance measurements (0.4–4 eV). In both cases, the spectral variation of the refractive index and the absorption coefficient were determined by fitting the experimental results with well-established theoretical models. Experimental values for the material’s gap were also found, and photoconductivity (PC) measurements were carried out. Transitions between bands, usually labelled ΓV8 → ΓC6 and ΓV7 → ΓC6, were found in the optical and PC responses. A wide spectral photoconductive response between 300 and 850 nm was found in the ZnSe/Si samples prepared at 250 °C substrate temperature. 相似文献
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169.
Infra-red (IR) photoluminescence (PL) spectra of ZnSe crystals doped with Yb, Gd rare-earth impurities and Cr impurity are investigated. The influence of stoichiometric deviation on the spectra is studied and the structure of complex IR PL bands is analysed. The good coincidence between the structures of IR PL spectra of the samples doped with Yb, Gd, and Cr is shown. Correlation between the component parts of the bands at 1 and 2 μm is found and possibility to control the composition of IR PL spectra by enrichment of the samples with Zn or Se is discussed. The models that explain the formation of complexes based on rare-earth and background Cr and Cu impurities, responsible for IR PL bands, are proposed. Keywords: IR luminescence, ZnSe, Rare-earth impurities, Cr impurity. 相似文献
170.
This study investigated the effects of ZnSe nanoparticles (NPs) on the structural and (linear and nonlinear) optical properties of polyvinyl alcohol (PVA) thin film. Three samples of ZnSe NP-doped PVA thin films with different concentrations of ZnSe were produced on a glass substrate. The ZnSe NPs were synthesized by pulsed laser ablation of the ZnSe bulk target immersed in distilled water using a 1064 nm wavelength and a high frequency pulsed Nd:YAG laser. The optical bandgap energies of the films were extracted from their UV-Vis-NIR absorption spectra. The corresponding energy bandgaps of the nanocomposite films declined as the ZnSe NPs doping concentration increased. X-ray diffraction analysis was used to characterize the crystalline phases of the ZnSe/PVA nanocomposite films. The concentration-dependent nonlinear optical absorption and nonlinear refraction behaviors of the films after exposure to 532-nm nanosecond laser pulses were investigated using the Z-scan technique. The nonlinear absorption response of the films was positive when measured using an open aperture scheme, which was attributed to the two-photon absorption mechanism. In addition, the nonlinear refraction indices had a negative value and they increased as the concentration of ZnSe NPs in the films increased. 相似文献