957 resultados para 338.43[822.1]


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多晶富镉HerxCdsoTe的电阻率较低,禁带宽度可调,是一种很有希望的半导体光电转换材料。本论文通过对Hg_(1-x)CdxTe(MCT)电沉积的研究,找出了多晶富镉MCT电况积的最佳条件,并对它的结构,组份以及在多硫体系溶液的光电化学性能进行了研究,观察到良好的光响应,在此基础上,进一步深入地研究了不同X值的系列MCT电极的结构,性能。结果表明,不同X值的系列MCT具有相同的闪锌矿型晶体结构,多晶晶粒大小,分布,形态等均没有明显的变化。但随着1-X值的增大,MCT的电导率增高,在多硫电解液中的短路光电流大大上升,但开路光电压却有所下降,这与φ_(fb)随1-X的升高而正移这一实验事实是一致的。即开路光电压的下降是由φ_(fb)的正移,由光谱响应实验得到的Eg值表明:当MCT中的汞含量增大(1-X值升高),禁带宽度下降.经分析,导致Eg变窄的因素在于Ec位置的下降,价带Ev的位置基本保持不变。过高的表面态密度和施主掺杂浓度,大大降低了MCT电极在多硫体系溶液中的Voc,Isc,η,FF。本实验中,未经任何处理MCT沉积膜在多硫电解液中的Voc可达300mV, Isc为3.55mAcm~(-2),η达0.43%.对MCT/多硫体系在光照下的稳定性进行了热力学分析,表明此体系易于分解,不是稳定体系,实验结果证实了这一点。为了解决以上存在的问题,本论文分别探索了能够影响电极性能的几个因素。MCT的退火处理能够增大多晶晶粒,减少晶粒间界,使Isc大大提高。采用Ni或650 ℃热处理后的Ti作基底呈现出较好的光活性,它的短路光流Isc。开路光电压Voc等比使用经10%HF浸刻的Ti作基底要提高数倍。与多硫体系相比,MCT电极在Fe(CN)_6~(4-)/Fe(CN)_6~(3-)体系中的Voc, Isc提高近二倍,但填充因子F,F未能得到改善。单晶HgIn_2S_4是有明显的n型半导体特征,由光谱响应实验确定出它的禁带宽度为2.0eV,与太阳光谱匹配差。在光极化特性测量中,暗态扫描与光刻至关得要,它能使电极在多硫体系中的光电流提高十多倍。在这种体系HgIn_2S_4的功率效率η=0.1%。稳定性实验表明单晶HgIn_2S_4在多硫体系中的光腐蚀小,光电流稳定。

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目的构建HIV-1C亚型gp120负载人树突状细胞(dentriti ccell,DC)疫苗,并对其体外功能进行初步检测。方法利用Amaxa细胞核转染技术将pcDNA3.1-gp120质粒转染至人成熟DC,以Western blot检测gp120的表达。通过流式细胞仪检测DC表面共刺激分子的变化、混合淋巴细胞反应、CD8+T细胞表面活化分子CD25的表达及其分泌IFN-γ的变化。结果通过Western blot检测,gp120在DC中得到了正确表达。经流式细胞仪检测,DC表面分子CD80表达率由刺激前的33.34%上升至43.20%,CD86表达率由刺激前的60.08%上升至90.34%;负载gp120DC刺激淋巴细胞增殖率为86.72%;CD8+T细胞表面分子CD25表达率由刺激前的5.27%上升至74.21%,IFN-γ的表达率达37%。结论负载了HIV-1gp120的人树突状细胞能够显著刺激淋巴细胞的增殖、增强CD8+T细胞表面活化分子CD25表达以及促进CD8+T细胞分泌IFN-γ,为下一步DC治疗性疫苗的体内研究奠定基础。

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Current-based microscopic defect analysis methods with optical filling techniques, namely current deep level transient spectroscopy (I-DLTS) and thermally stimulated current (TSC), have been used to study defect levels in a high resistivity silicon detector (p(+)-n-n(+)) induced by very high fluence neutron (VHFN) irradiation (1.7x10(15) n/cm(2)). As many as fourteen deep levels have been detected by I-DLTS. Arrhenius plots of the I-DLTS data have shown defects with energy levels ranging from 0.03 eV to 0.5 eV in the energy band gap. Defect concentrations of relatively shallow levels (E(t) < 0.33 eV) are in the order of 10(13)cm(-3), while those for relatively deep levels (E(t) > 0.33 eV) are in the order of 10(14) cm(-3). TSC data have shown similar defect spectra. A full depletion voltage of about 27,000 volts has been estimated by C-V measurements for the as-irradiated detector, which corresponds to an effective space charge density (N-eff) in the order of 2x10(14) cm(-3). Both detector leakage current and full depletion voltage have been observed to increase with elevated temperature annealing (ETA). The increase of the full depletion voltage corresponds to the increase of some deep levels, especially the 0.39 eV level. Results of positron annihilation spectroscopy have shown a decrease of total concentration of vacancy related defects including vacancy clusters with ETA, suggesting the breaking up of vacancy clusters as possible source of vacancies for the formation of single defects during the reverse anneal.

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应用Raman散射谱研究超高真空化学气相淀积(UHV/CVD)生长的不同结构缓冲层对恒定组分上表层Si_(1-x)Ge_x层应力弛豫的影响。Raman散射的峰位不仅与Ge组分有关,而且与其中的应力状态有关。在完全应变和完全弛豫的情况下,Si_(1-x)Ge_x层中的Si-Si振动模式相对于衬底的偏移都与Ge组分成线性关系。根据实测的Raman峰位,估算了应力弛豫。结果表明

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于2010-11-23批量导入

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于2010-11-23批量导入