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The continuity equation of minority carriers in n-type germanium is solved for the stationary case, in which the volume recombination is assumed to be of the recombination-center type and the surface recombination is introduced in the boundary condition. An expression for the photoconductivity is obtained from this solution.By substituting the known absorption data and the volume lifetime of minority carrier in the sample into the expression of photoconductivity and by choosing suitable values of surface recombination velocity, photoconductive spectra are calculated and are compared with the experimental curves. The agreement is satisfactory for wave-lengths greater than 1.2 μ. Below 1.2 μ, the experimental curves fall well below the calculated curves. It is thought that other types of volume recombination may exist.The photoconductive spectra usually have a maximum outside the absorption edge. By measuring the relative height of the maximum, the surface recombination velocity can be obtained. This method is suitable for medium and large values of surface recombination velocity.The photoconductivity drops sharply on both sides of the maximum in case of large values of recombination velocity. In such cases, the energy gap of the semiconductor can be obtained in a simple way. For germanium the energy gap is 0.83 eV for direct transition and 0.635 eV for indirect transition.From this investigation, the energy gap of CdS is reestimated to be 2.53 eV and that of Cu2O greater than 2.10 eV. 相似文献
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Photoluminescence spectra of a series of MBE-grown Hg1-xCdxTe samples with the same mole fraction of about x≈0.39 have been measured at different temperatures from 5 to 100 K. By aid of the temperature and exciting laser power dependence of photoluminescence peak energy and relative intensity, as well as of the comparison with other measurements, four main structures dominating in the photoluminescence spectra are attributed to band to band, DoX, AoX and DoAo transitions. A deep donor state level located at about 8.5meV below the bottom of the conduction band has been observed and is determined to be due to the arsenic-occupied mercury vacancies. Two acceptor levels located at about 14.5 meV and about 31.5 meV above the top of the valance band have also been found from the measuements, which are identified as the mercury vacancies and As in anion site, respectively. 相似文献
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报道了x=0.214组份、低补偿度(K《1)n-Hg1-xCdxTe晶体在0.3─30K温度范围,0─7T强磁场下的横向磁阻、电子霍耳迁移率、霍耳系数测量结果,观测到了磁致金属-绝缘体相变和相变后的温度激活输运行为。分析实验数据,提出:低补偿度、组份:x=0.2附近的n-Hg1-xCdxTe,磁致金属-绝缘体相变(MIT)发生的机理是载流子在浅施主杂质态上的磁冻结;发生磁冻结的前提是热冻出(thermal freeze
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采用原子力显微镜(AFM)、俄歇电子能谱(AES)和显微压痕分析等手段对射频等离子体增强化学气相沉积法制备的掺氮类金刚石(DLC:N)薄膜的微观结构和力学性能进行了研究.结果表明,随着含氮量的增加,DLC薄膜的AFM表面形貌中出现了几十纳米的颗粒,原子侧向力显微镜和AES分析表明这种纳米颗粒是x大于0.126的非晶氮化碳CNx结构.这种非晶DLC/CNx的纳米复合结构,减小了薄膜的内应力,从而提高了薄膜与衬底的附着力.
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类金刚石碳膜
微观结构
附着特性 相似文献
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采用等离子增强化学气相法(PECVD)在碲镉汞(MCT)衬底上沉积出纳米团聚的类金刚石薄膜(DLC).用原子力显微镜(AFM )和侧向力显微镜(LFM)对DLC和MCT表面形貌进行表征;用俄歇电子能谱(AES)对DLC/MCT界面附近各元素含量的分布进行分析研究.结果表明:当膜厚达到25nm以上,这种DLC膜就能够有效地抑制MCT中HgTe的分解和Hg与Te的外扩散.AFM 和LFM的观察结果表明,原始MCT晶片经100℃在氮气气氛中退火30min,表面区域出现了不同与MCT的微米量级的新相,而由DLC膜保护的MCT晶片表面就没有观察到这种由分解反应引起的相变. 相似文献