飞秒激光作用下的硅表面微结构及发光特性

 采用近红外飞秒激光辐照浸泡在硫酸溶液中的N型单晶硅片，激光波长800 nm，脉宽200 fs，重频1 kHz，平均功率为100 mW,而硫酸溶液的质量分数分别选择为0.1%和1%。辐照后硅表面呈直径为5~8 mm,高度15 mm的柱型结构。分析其荧光特性，并通过比较硅材料表面微结构与激光光源、扫描参数、硅片背景环境的关系，确定最佳辐照条件为激光扫描速度750 mm/s,扫描间距5 mm/s。最终在厚度0.5 mm、直径26 mm的硅片上获得10 mm×10 mm的方形扫描区域，荧光光谱显示激光扫描后的区域在700 nm附近有很强的荧光发射。分析结果表明飞秒激光扫描改变了样品的表面微结构尺寸，增大了吸收面积，扩展了荧光激发波长，有效提高了样品的吸收效率和荧光发光相对强度(超过扫描前发光相对强度的2倍)，荧光发射谱的变化是由量子限制效应和表面态模型共同作用的结果。

Microstructure and fluorescence property of silicon fabricated by femtosecond laser

The micro-structure surface and fluorescence of silicon slice fabricated by femtosecond laser under the assistant of low consistency sulfuric acid liquor are reported. A 10 mm×10 mm square region was fabricated from 0.5 mm thick and 26 mm in diameter silicon slice. The absorbency is increased due to the change of the surface microstructure of the silicon. Photoluminescence spectra display a high fluorescence emission at the wavelength from 700 nm to 750 nm, thus show a new and simple method to increase the fluorescence property of silicon.