低温铝诱导晶化制备纳米晶硅薄膜的物相和光学性能研究

Research on the Phase and Optical Properties of nc-Si Films Prepared by Low Temperature Aluminum Induced Crystallization

采用射频磁控溅射镀膜系统,在玻璃衬底上制备了非晶硅(α-Si)/铝(Al)复合薄膜,结合氮气(N2)气氛中低温快速光热退火制备了纳米晶硅(nc-Si)薄膜;利用光学显微镜、共焦光学显微仪、X射线衍射(XRD)仪、拉曼散射光谱(Raman)仪和紫外-可见光-近红外分光光度计(UV-VIS-NIR)对纳米晶硅薄膜的表面形貌、物相及光学性能进行了表征,研究了退火工艺对薄膜性能的影响。结果表明:300℃,25min光热退火可使α-Si/Al膜晶化为纳米晶硅薄膜,晶化率为15.56%,晶粒尺寸为1.75nm;退火温度从300℃逐渐升高到400℃,纳米晶硅薄膜晶粒尺寸、晶化率、带隙逐渐增加,表面均匀性、晶格畸变量逐渐减小;退火温度从400℃逐渐升高到500℃,纳米晶硅薄膜的晶粒尺寸、晶化率继续增加,带隙则逐渐降低;采用纳米晶硅薄膜的吸光模型验证了所制备的纳米晶硅薄膜的光学特性,其光学带隙的变化趋势与吸光模型得出的结果一致。

In the present paper,nanocrystalline silicon thin films on glass substrates were prepared by rapid thermal annealing （RTA）of RF magnetron sputtered system andα-Si/Al films at a low temperature in N2 atmosphere.Optical metallographic mi-croscope,confocal optical microscopy,X-ray diffractometer,Raman scattering and UV-Vis-NIR spectrometers were used to characterize the surface morphology and the phase and optical properties of nc-Si films.The influence of annealing process on the nc-Si films properties was studied.The results showed that nc-Si films were obtained after aluminum induced crystallization of theα-Si/Al films at 300 ℃,withthe crystallization rate 15. 56% and the grain size 1. 75 nm.The surface uniformity and lattice distortion of nc-Si films reduced,while grain size,degree of crystallization and the optical band gap of the films increased with increasing annealing temperature from 300 to 400 ℃.As the annealing temperature increased from 400 to 500 ℃,although the degree of crystallization and grain size increased,the tendencies of all other characteristics were opposite.On the contrary,the surface uniformity and the lattice distortion increased,but the optical band gap of nc-Si films reduced.The optical properties of the resulting films were confirmed by the absorption model of nc-Si thin films,where the tendency of band gap changes is in con-sistent with the optical modeling.