钴掺杂的非晶碳膜的光电导性能研究

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摘要：本文研究了磁性金属钴掺杂的非晶碳膜/GaAs/Ag p-n和肖特基双结串联结构的制备与光电导特性。首先采用脉冲激光沉积技术在硅掺杂的N型GaAs基片一端上制备非晶碳膜，然后，采用真空热蒸发法在非晶碳膜和GaAs基片的另一端蒸镀银电极。样品在有无激光照射下的伏安特性曲线显示出非常好的光电导现象。不同偏压下样品的光电导随着正向偏压增大而指数衰减，在0.3V正向偏压下具有最大的光电导，为652。接着我们分析了该结构体系的光电导特性来源。发现钴掺杂的非晶碳膜/GaAs之间为弱P-N结接触，而Ag与GaAs基片之间为肖特基接触，如此便构成了p-n结和肖特基结双结串联结构。Ag/GaAs之间的肖特基结限制暗电流，而钴掺杂的非晶碳膜/GaAs之间的p-n结增强光电流，这便是样品光电导特性的来源。本论文的结果为制备新型光敏电阻器件打下坚实基础。54212

毕业论文关键词：P-N结，肖特基结，光电导

Abstract: In this thesis, we studies the preparation and photoconductivity of magnetic metal cobalt doped amorphous carbon films /GaAs/Ag p-n and Schottky double junctions in series structure. Firstly, using pulsed laser deposition technique, amorphous carbon films were deposited on silicon doped N type GaAs substrate. Then, using the vacuum thermal evaporation method, silver electrode were evaporated on the amorphous carbon film and GaAs substrate. By measuring the I-V characteristic curves with and without laser irradiation, the samples showed very good photoconductive phenomenon. Results showed that with the increases of forward bias, the photoconductivity decayed exponentially and the maximum photoconductivity was 652 at 0.3V forward bias. Then we analyzed sources of the photoconductive properties. We found that they are weak p-n junction contact between the Co doped amorphous carbon film and GaAs, and Schottky contact between silver and GaAs. Thus, it realizes the p-n junction and Schottky junction in series structure. This may be the sources of the photoconductivity. The results of this thesis offer important foundation for the preparation of new photosensitive resistance device.

Key words: P-N junction, Schottky junction, photoconductivity

1 绪论 4

2 非晶碳膜的制备与结构 5

2.1 脉冲激光沉积 5

2.2 非晶碳膜的制备 6

2.3 拉曼散射分析非晶碳膜的结构 7

3 非晶碳膜/GaAs/Ag双结系统的光导效应 9

3.1双结系统的光导特性 9

3.2双结系统光导特性产生的原因 10

结论 13

参考文献 14

致谢 16

1 绪论

光敏电阻器件是一种特殊的电阻器，其原理是基于半导体光电导效应，并且对光线相当的敏感，外界光照射的明暗（强弱）会导致光敏电阻器件的电阻值产生相应的改变，照射光弱，电阻增大、呈高阻状态；照射光强，电阻值将迅速减小。鉴于这一特性，光敏电阻器在国防、科学研究、工农业生产、家用电器中各种电路的自动控制，或涉及光测量、光控制、光电转换等多种测量仪器方面广泛运用。如今，一般使用金属硫化物、硒化物和碲化物等材料来制造光敏电阻器件，采用喷涂、涂敷、烧结等方式，绝缘的衬底上生成光敏电阻体，并且在欧姆电极接出引线，封装于透光密封壳体内构成[1]。由于光敏电阻的光谱特性, 可分为紫外光光敏电阻器、可见光光敏电阻器、红外光光敏电阻器三种。其中可见光光敏电阻材料主要有硫化镉和硒化镉[2]。其具有的优点是体积比较小，灵敏度很高，光谱特性比较好，缺点是受到温度的影响比较大，响应速度不迅速，光照特性为非线性，不适合当做光检测元件。另外的缺点是制作成本高，含有重金属镉，容易对环境造成污染等。