Enhanced spectral response by silicon nitride index matching layer in amorphous silicon thin-film solar cells

Abstract We employed the low temperature hydrogenated amorphous silicon nitride (a-SiN x :H) prepared by plasma-enhanced chemical vapor deposition as a refractive index ( n ) matching layers in a silicon-based thin-film solar cell between glass ( n = 1.5) and the transparent conducting oxide ( n = 2). By varying the stoichiometry, refractive index and thickness of the a-SiN x :H layers, we enhanced the spectral response and efficiency of the hydrogenated amorphous silicon thin-film solar cells. The refractive index of a-SiN x :H was reduced from 2.32 to 1.78. Optimizing the a-SiN x :H thickness to 80 nm increased the J SC from 8.3 to 9.8 mA/cm 2 and the corresponding cell efficiency increased from 4.5 to 5.3%, as compared to the cell without the a-SiN x :H index-matching layer on planar substrate. The a-SiN x :H layers with graded refractive indices were effective for enhancing the cell performance.