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利用等离子体增强化学气相沉积技术研制出了优质稳定的氢化非晶 纳米晶两相结构硅薄膜 .薄膜的光电导率相对于器件质量的非晶硅有两个数量级的提高 ;光敏性也较好 ,光、暗电导比可以达到 10 4,此外薄膜的光电导谱具有更宽的长波光谱响应 .更为重要的是薄膜的光致退化效应远小于典型的非晶硅薄膜 ,在光强为 5 0mW/cm2 的卤钨灯光照 2 4h后 ,光电导的衰退小于 10 % .这种薄膜优良的光电性能源于薄膜中的非晶母体的存在使其在光学跃迁中的动量选择定则发生松弛 ,因而具有大的光学吸收系数和较高的光敏性 ;相对于典型非晶硅而言 ,薄膜的中程有序度得到了较大的改善 ,并具有小的深隙态密度 ;薄膜中存在的纳米尺寸的微晶颗粒 ,提供了光生载流子的复合通道 ,在非晶母体中的电子空穴对可以转移到微晶颗粒中进行复合 ,这样抑制了非晶母体中的非辐射复合 ,从而降低了光致亚稳缺陷产生的概率
High-quality and stable hydrogenated amorphous nanocrystalline two-phase structured silicon films have been developed by using plasma-enhanced chemical vapor deposition (PECVD). The photoconductivity of the films is two orders of magnitude higher than that of device-based amorphous silicon. , Light and dark electrical conductivity ratio can reach 104, in addition the photoconductive spectrum of the film has a broader long-wave spectral response.More importantly, the photodegradation effect of the film is much smaller than the typical amorphous silicon film, at a light intensity of 5 The photoconductivity declined by less than 10% after 24 hours of 0 mW / cm2 halogen lamp illumination. The excellent optoelectrical property of this film originates from the amorphous matrix in the film, which relaxes its selection rule of momentum in optical transition , And thus has a large optical absorption coefficient and high photosensitivity; compared with the typical amorphous silicon, the mid-range order of the film has been greatly improved and has a small deep-gap density; the presence of the film Of nano-sized crystallite particles to provide a composite channel of photo-generated carriers. The electron-hole pairs in the amorphous matrix can be transferred to the crystallite particles for recombination, so that non-radiation in the amorphous matrix is suppressed Together, thereby reducing the probability of photoinduced metastable defects generated