Influence of electron bombardment on recombination and attachment in II–VI—IV–VI film photoconductors

An investigation is made of the action of electron bombardment on wide-gap photosensitive films of II–VI compounds with submicron IV–VI inclusions which form bounded solid solutions with these compounds. It is shown that the radiation resistance of II–VI compounds is enhanced by adding IV–VI compounds. It is observed that the radiation acts differently on shallow and deep levels in the wide-gap semiconductor. An explanation is proposed for the experimental data using a heterophase semiconductor model. Pis’ma Zh. Tekh. Fiz. 25, 66–72 (February 12, 1999)     

Spin Manipulation Using Magnetic II–VI Semiconductors

Recently, efficient spin injection, being the first step towards semiconductor spin electronics, by using BeMnZnSe as a spin filter was accomplished. Such a spin filter made it possible to align the spin orientation of conduction electrons and subsequently inject them into GaAs. However, controlling spin orientation of conduction electrons by an external voltage would be very desirable for semiconductor-based magnetoelectronics. This can be accomplished by using spin switch structures, based on resonant tunneling through magnetic quantum wells, with two separate spin-up and spin-down resonances. Here we summarize both our recent results on spin injection as well as on spin aligner and magnetic resonant tunneling structures. For accomplishing the latter, we have developed magnetic resonant tunneling diodes based on BeTe–ZnMnSe–BeTe structures. Resonant tunneling diode is meant to serve as a spin switch because of the existence of two separate spin-up and spin-down resonances. The tunneling carriers have subsequently been injected into a nonmagnetic GaAs p–i–n light emitting diode. Circular polarization of the emitted light is an indicator of the spin polarization of injected electrons. At constant magnetic field and current, degree of spin polarization could be changed from 81% to 38% by only varying the voltage across the magnetic resonant tunneling device.     

Rashba Effect in IV–VI Semiconductor Quantum Wells

The spin–orbit split quantized states for electrons confined in IV–VI lead-salt asymmetric quantum wells (QWs), grown on both (100) and (111) substrates, are obtained analytically within the envelope function approximation with a k p four-band model for the bulk. Nonparabolicity, anisotropy, and break of valley degeneracy are included. In (111) QWs, it is shown that for the valley along the growth direction the Rashba splitting is like the one in III–V QWs, i.e., isotropic and linear in k (for k 0). For the oblique valleys, contrary to the III–V case, a Rashba effect is obtained that is anisotropic and described by an effective magnetic field with nonzero component along the growth direction. Specific results for PbTe/PbEuTe asymmetric QWs with large Rashba splittings are shown.     

Preparation of II–VI and IV–VI semiconductor films for solar cells by the isovalent substitution technique with a CBD-made substrate

II–VI and IV–VI semiconductor films for solar cell applications, namely, CdTe, CdS, CdSe, PbS, PbSe and PbTe, can be prepared in a two-stage deposition process. In this work we illustrate the two-stage process to obtain PbTe and CdSe films from precursor oxide or hydroxide films deposited by chemical bath deposition (CBD). At the first stage, plumbonacrite Pb₁₀(CO₃)₆O(OH)₆ or cadmium oxide/hydroxide CdO₂/Cd(O₂)_0.88(OH)_0.24 films were deposited onto a glass substrate by CBD, using an ammonia-free low-temperature process in an alkaline aqueous solution with corresponding ion sources. Then, at the second stage, the obtained film was placed in a chemical vapor deposition (CVD) Hot Wall reactor with gas transportation, where it acted as a substrate in the reaction of isovalent substitution of Te or Se for the nonmetallic film component, thus forming PbTe and CdSe films. A nitrogen flux of 0.25 L/min was used as the transporting gas. The source temperature was adjusted between boiling (Tb) and melting point (Tm) to control the flux gas of the source. The substrate temperature was adjusted to improve film quality. Structural and optical investigation of the films proved their high quality, which determines the possibility of using them as solar cell elements, in particular, in multijunction cells.     

Low-temperature Grüneisen gamma of II–VI semicoductor ZnS

The theoretical study of low-temperature lattice thermal expansion of the II–VI semiconductor ZnS is attempted. The generalized Grüneisen gammas of the elastic waves propagating in different directions with respect to the [001] crystallographic axis of ZnS are calculated using the second- and third-order elastic constants. The values of mode Grüneisen gammas γ _j are determined and found generally positive except from γ ₂ at θ = 25° to θ = 65°. The low-temperature limit of the Grüneisen gamma is determined and compared with experimental values. Using this we calculated the Brugger gamma γ ^Br and hence the low-temperature volume lattice thermal expansion γ _L. It is expected that the volume expansion is positive down to absolute zero for ZnS.     

II–VI semiconductor alloy films: Cd1−xZnxTe

Electrical conductivity and optical properties of undoped and copper-doped Cd_1–xZn_xTe (0.1相似文献   

Electrical and humidity sensing properties of lead(II) tungstate–tungsten(VI) oxide and zinc(II) tungstate–tungsten(VI) oxide composites

Lead(II) tungstate and zinc(II) tungstate were prepared by a solution route and sintered at 973 K in the form of cylindrical discs. Experimental results on PbWO₄ (PW) and WO₃ (WO) composites for humidity sensing are described. Sintered polycrystalline discs of PbWO₄ (PWWO-10), WO₃ (PWWO-01), ZnWO₄ (ZWWO-10) and composites of PW or ZW and WO in the mole ratios 8:2, 6:4, 4:6, 2:8 designated as PWWO and ZWWO-82, 64, 46 and 28, respectively and doped with 2 mol% of Li⁺ were studied. The composites were subjected to dc conductance measurements over the temperature range 373–673 K in air atmosphere from which activation energies were determined. The activation energy values for dc conductance were found to be in the range of 1.09–1.30 eV. The composites were identified by powder XRD data. The scanning electron microscopy (SEM) studies were carried out to study the surface and pores structure of the sensor materials. The composites were subjected to dc resistance measurements as a function of relative humidity in the range of 5–98% RH, achieved by different water vapor buffers thermostated at room temperature. The sensitivity factor (S_f=R_5%/R_98%) measured at 298 K revealed that PWWO-28 and ZWWO-46 composites have the highest humidity sensitivity factor of 17 615±3000 and 2666±550, respectively. The response and recovery time for these humidity sensing composites were good.     

创艺达VI设计方案

<正>设计说明:公司VI系统由基础系统,办公系统,广告系统和环境系统构成,企业的标志是由一片绿叶构成,因此标准色也以绿色为主,绿色是希望的象征,办公系统设计主要是把企业标志和企业标准色运用在公司的日常办公用品处,例如信笺,信封,名片,工作证等,公司有了自己企业的视觉符号系统能让企业员工对企业产生归属感,认同感,提升企业士气。     

蒲江VI设计作品

蒲江 桂林电子科技大学设计系讲师主要研究方向：公共艺术设计、平面设计     

邦博服装品牌VI设计

正设计说明:标志采用色彩魅力蓝代表着理智、好运、忠诚、银色代表着沉稳,标志以邦博首字母B为设计元素,整体造型用字母B交织在一起围绕成一个圈,象征着公司员工紧密团结在一起,公司拥有强大的凝聚力。     

长沙卤教授VI设计

正设计说明:长沙卤教授是一家互联网+餐饮的020卤味外卖创新品牌。卤教授的品牌形象就像是一个风趣、幽默、乐于助人、德高望重、博才多学的专家级别的学者型教授。品牌的定位希望通过一种睿智、快乐的形象展现在大学生及年轻工薪群体中,具有极强的亲切感可以快速的拉近与消费者的关系;背景及色调的选用可以从侧面感受到长沙卤味里古朴秘技的历史与革新。     

书籍设计·VI设计

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浅谈VI系统中的设计规范

通过总结VI系统中几何规范的内容，阐明了设计规范的重要作用，并呼吁各界对此予以重视。     

Giant Zeeman Splitting of Excitons in a III–V Nonmagnetic Quantum Well Electronically Coupled With a II–VI Semimagnetic Quantum Well

We report on design, fabrication by molecular beam epitaxy, and photoluminescence (PL) studies of GaAs/AlGaAs/ZnSe/ZnCdMnSe double quantum wells (QWs), where resonant electronic coupling occurs through a heterovalent interface. The resonant conditions achieved in the properly designed sample facilitate penetration of the electron wave function from the nonmagnetic GaAs QW into the diluted magnetic semiconductor ZnCdMnSe QW. It results in the sign reversal and drastic increase of a GaAs QW excitonic g factor. The exciton spin splitting observed in the magneto-PL spectra is in general agreement with the calculation performed within the envelope function approximation, taking into account both the inter-well electron coupling and Brillouin-like paramagnetic behavior of the Mn²⁺ ions.     

Size quantization effects in optical and electrical properties of II–VI semiconductor films in nanocrystalline form

The electrical properties of CdTe and optical properties of ZnS in nanocrystalline thin film form are studied with a view to have a clearer understanding of the optical processes and the carrier transport mechanisms in nanocrystalline II–VI semiconductors, in general. Nanocrystalline ZnS and CdTe films were deposited by magnetron sputtering of respective targets in argon plasma. The optical absorption data of nanocrystalline ZnS films (thickness 10–40 nm) could be explained by the combined effects of phonon and inhomogeneity broadening along with optical loss due to light scattering at the nanocrystallites. The conductivity of CdTe (grain size within 4–4·7 nm) showed (T ₀/T) ^p dependence withp ∼ 0·5 indicating the presence of a Coulomb gap near the Fermi level. The width of the Coulomb gap varied within 0·02–0·04 eV depending on the deposition condition. The existing theoretical models were used for estimating hopping energy (0·02–0·04 eV) and hopping distance (2·8–5·1 nm) in nano CdTe films.     

Unusual photoluminescence of Cu–ZnO and its correlation with photocatalytic reduction of Cr(VI)

Cu–ZnO was synthesized by sol–gel route with a varied copper concentration of 1, 2 and 3 mol%. The synthesized materials were structurally characterized with powder X-ray diffraction and Raman spectroscopy, morphologically using a field emission scanning electron microscope, and electronic properties were studied with UV–visible spectroscopy and photoluminescence spectroscopy. Variation in Cu doping showed enhancement/quenching in photoluminescence of ZnO. This special characteristic is reflected in photocatalytic reduction of Cr(VI).     

VI设计中的包装色彩应用

随着企业社会竞争压力的不断加剧,想要从各种同类品牌中脱颖而出成为最吸引人注意的一个是每个企业所期望的,我们设定了企业形象识别系统(简称VI),来规范和展示企业在视觉平面设计中的特色,VI设计相当的重要,他是企业对外展示内在价值的一个隐形窗口,在VI设计的过程中,企业需要把设计元素化作视觉载体来进行统筹设计,企业在本身管理的同时,还需要不断做出有效的设计方案,来满足不断变化的市场,其中色彩作为一种有战略意义的视觉符号,设计者必须保证色彩设计的应用模式,特别是VI设计中包装色彩应用好坏甚至能给企业快速带来产品的效益,对企业的发展产生了重要的影响,当我们重新回归到这个设计过程中的时候,我们究竟该如何选取色彩进行搭配,什么影响了我们的色彩搭配思维呢?色彩又有怎样的多重意义,我们如何进行灵感的捕捉,这些色彩的应用对VI设计有何影响,都是本文所需要阐释的。     

绿地·桂满园VI设计

<正>设计说明:标志是一个百合花饰图形,定位复古巴洛克风格,其设计思路来源于法国王室及法国路易十三的皇家百合饰纹,百合花是法国波普王朝的王族标志,象征高贵、财富、胜利、荣誉、圣洁、庄严、高雅。具有巴洛克风格的百合花纹饰线条流畅,水晶炫图的质感华丽而高雅,视觉效果突出,应用于房地产品牌VI系统中,彰显地产品牌的品质与高贵。