94MeV Xe离子辐照引起的薄膜硅光学带隙变化研究

室温下,用94MeV的Xe离子辐照纳米晶和非晶硅薄膜以及单晶硅样品,辐照量分别为1.0×1011,1.0×1012和1.0×1013ions/cm2。所有样品均在室温下用UV/VIS/NIR光谱仪进行检测分析。通过对比研究了纳米晶、非晶、单晶硅样品的光学带隙随Xe离子辐照量的变化。结果表明,不同结构的硅材料中Xe离子辐照引起的光学带隙变化规律差异显著:随着Xe离子辐照量的增加,单晶硅的光学带隙基本不变,非晶硅薄膜的光学带隙由初始的约1.78eV逐渐减小到约1.54eV,而纳米晶硅薄膜的光学带隙则由初始的约1.50eV快速增大至约1.81eV,然后再减小至约1.67eV。对硅材料结构影响辐照效应的机理进行了初步探讨。

Modification of Optical Bandgap of Thin Silicon Films Induced by 94 MeV Xe Ion Irradiation

Mono-crystalline silicon(c-Si),thin films of amorphous silicon(a-Si)and nano-crystalline silicon(nc-Si)were irradiated at room temperature(RT)by using 94 MeV Xe-ions at 1.0×10~(11),1.0×10~(12) or 1.0×10~(13) Xe-ions/cm~2,respectively.All samples were analyzed at RT by an UV/VIS/NIR spectrometer(Lambda 900,PE,Germany),and then the uariation of the optical bandgap with the irradiation fluence was investigated systematically.The results show that the optical bandgap of the silicon samples irradiates by Xe-ion changed dramatically with different crystalline structures.For the a-Si thin films,the optical bandgap values decreased gradually from～1.78 to～1.54 eV with increasing Xe-ion irradiation fluence.For the nc-Si thin films,the optical bandgap values increased sharply from～1.50(origin)to～1.81 eV(Φ=1.0×10~(12)ions/cm~2),and then decreased to～1.67 eV(Φ=1.0×10~(13) ions/cm~2).However,there is no observable change of the optical bandgap of the c-Si after Xe-ion irradiations.Possible mechanism on the modification of the silicon thin films was briefly discussed.