半导体中超快过程的研究  

STUDY OF ULTRAFAST PROCESS IN SEMICONDUCTOR

作　　者：黄仕华[1] 李汐[1] 凌严[1] 陆昉[1] 

机构地区：[1]复旦大学表面物理国家重点实验室,上海200433

出　　处：《红外与毫米波学报》2005年第3期179-181,共3页Journal of Infrared and Millimeter Waves

基　　金：国家自然科学基金(90101011;10321003;10474012);国家重点基础研究项目(G2001CB3095);上海市科委重大项目

摘　　要：用飞秒脉冲激光技术研究了半导体中的超快过程.通过用超快光生电压谱对激光激发载流子的动量弛豫过程进行检测,得到在半导体硅中载流子的动量弛豫时间约为70飞秒,该过程与载流子与载流子的散射几率有关;对于锗硅量子点,由于载流子的散射几率下降,使动量弛豫时间增加至130飞秒.用超快反射谱法测量了载流子的能量弛豫过程和扩散过程,用高能量激光激发得到载流子的能量弛豫时间约为几个皮秒,这与载流子与声子的散射几率密切相关;而用低能量激光激发可得到光生载流子的扩散时间约为1百皮秒量级.The ultrafast process in semiconductor was studied by using femtosecond pulse laser. The momentum relaxation of carriers excited by laser was detected by using ultrafast photo-voltage spectra. The time of momentum relaxation of carriers in semiconductor Si is about 70, femtosecond, which is related to the probability of carrier-carrier scattering. In SiGe quantum dot, it is about 130 femtosecond due to the decrease of carrier-carrier scattering. The energy relaxation and diffusion processes can be measured by ultrafast reflection spectra. The time of energy relaxation of carriers excited by high energy laser is about several picoseconds, which is related to the probability of carrier-phonon scattering, and the diffusion time of carriers excited by low energy laser is about several hundreds picoseconds.

关 键 词：飞秒脉冲激光 半导体 动量弛豫 能量弛豫 超快光生电压谱 

分 类 号：O472[理学—半导体物理] TN249[理学—物理]