Ultrafast absorption in free‐standing porous silicon films
Ultrafast absorption in free‐standing porous silicon films
复制标题
独立式多孔硅薄膜的超快吸收
DOI：
10.1063/1.114755
复制
发表时间：
1995
影响因子：
4
通讯作者：
W. Lang
中科院分区：
文献类型：
--
作者：
J. Owrutsky;J. Rice;S. Guha;P. Steiner;W. Lang
为了研究载流子动力学和发光机理，在室温下对自支撑多孔硅薄膜进行了超快吸收研究。用紫外光和可见光对制备的样品和两个退火样品进行了激发。紫外光泵浦的样品的瞬时吸收曲线包含了0.8±0.2ps的快速衰减(τf)和30ps的≳较慢的衰减。τf对于500 °C紫外光激发样品和可见光激发样品都有较短的变化。较快的衰减率表明，瞬时吸收的亚皮秒分量可能是由于载流子热化而不是核态到表面态的激发转移。
Ultrafast absorption studies on free‐standing porous silicon films have been carried out at room temperature to investigate the carrier dynamics and the luminescence mechanism. Ultraviolet and visible excitations were used on an as‐prepared sample and two annealed samples. Transient absorption curves of UV pumped, as‐prepared samples contain a fast decay (τf) of 0.8±0.2 ps and a slower decay of ≳30 ps. τf is found to be shorter for both the 500 °C annealed sample with UV excitation and for the as‐prepared sample with visible excitation. The faster decay rates suggest that the subpicosecond component of the transient absorption may be due to carrier thermalization rather than core‐to‐surface state excitation transfer.