掺硼p型非晶硅薄膜的制备及光学性能的表征

以高氢稀释的硅烷(Si H4)为反应气体,硼烷(B2H6)为掺杂气体,利用RF-PECVD方法,在玻璃衬底上制备出掺硼的氢化非晶硅(a-Si∶H)薄膜,研究了硼掺杂量对氢化非晶硅(a-Si∶H)薄膜的光学性能的影响.利用NKD-7000 W光学薄膜分析系统测试薄膜的透射谱和反射谱,并利用该系统的软件拟合得出薄膜的折射率、消光系数、吸收系数等光学性能参数,利用Tauc法计算掺硼的非晶硅薄膜的光学带隙.实验结果表明,随着硼掺杂量的增加,掺杂非晶硅薄膜样品在同一波长处的折射率先增大后减小,而且每一样品均随着入射光波长的增加而减小,在波长500 nm处的折射率均达到4.3以上;薄膜的消光系数和吸收系数随着硼掺杂量的增大而增大,在500 nm处的吸收系数可高达1.5×105cm-1.在实验的硼掺杂范围内,光学带隙从1.81 eV变化到1.71 eV.

Preparation and Characterization of Boron-Doped p-type a-Si∶H Thin Film

The boron-doped amorphous silicon(a-Si∶H)thin film was deposited on glass substrate by plasma enhanced chemical vapor deposition(PECVD).SiH4 and B2H6 with high hydrogen dilution are used as the reactive gas and dopant gas,respectively.The transmission spectra and the reflection spectra of the films were measured by NKD thin film analysis system,the refractive index,extinction coefficient,absorption coefficient and other optical parameters of the films were fitted out and optical band gap of the samples were calculated using Tauc method.The results have shown that with the dopant increase,the refractive index of amorphous silicon thin film decreases as the light wavelength increases,and the refractive index at 500 nm wavelength was more than 4.3;and the absorption coefficient was as high as 1.5× 105 cm-1 at 500 nm wavelength.Optical band gap of boron-doped amorphous silicon(a-Si∶H)thin film ranges from 1.7 to 1.8 eV.In a word,it is necessary to reduce the dopant concentration to get the widow layer with low absorption.