摘要
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 。
High-quality nc-Si/a-Si:H diphasic films with improved stability were prepared by using the plasma-enhanced chemical vapor deposition technology. In comparison with typical amorphous silicon, the diphasic silicon films possess higher photoconductivity (two orders larger than that of the amorphous silicon film) and fairly good photosensitivity(the ratio of the photo-to dark-conductivity is about 10) and higher stability (the degradation of the photoconductivity is less than 10% after 24h long light soaking with 50 mW/cm(2) intensity at room temperature). In addition, the diphasic silicon film has a better light spectra response in the longer wavelength range. The improvement in photoelectronic properties may be attributed to: the existence of the disorder within the amorphous matrix, which breaks the momentum selection rule in the optical transition and, consequently, results in the large light absorption coefficient and high photosensitivity; the improved medium range order and low gap states density. Excess carriers generated in the amorphous matrix tend to recombine in the embedded crystallites, which suppresses nonradiative recombination within the amorphous matrix and reduces the subsequent defect creation.
出处
《物理学报》
SCIE
EI
CAS
CSCD
北大核心
2003年第6期1465-1468,共4页
Acta Physica Sinica
基金
国家重点基础研究发展项目 (批准号 :G2 0 0 0 0 2 82 0 1)资助的课题~~
