SiGe/Si多量子阱中的光致子带间吸收研究

PHOTO-INDUCED INTERSUBBAND ABSORPTION IN THE SiGe/Si MULTIPLE QUANTUM WELLS

本文论述了硅锗量子阱中的光致子带间吸收的机理 ,并在实验中探测 Si Ge/Si量子阱价带间的红外光致吸收 .载流子由氩离子激光器作为光泵浦源产生 ,所导致的红外吸收由一个步进式傅里叶变换光谱仪来探测 .在硅锗量子阱中的光致吸收有两个来源 :类似单一掺杂的 Si Ge薄层的体吸收的自由载流子吸收 ,及量子阱价带的子带间吸收 .实验探测了 TE和TM偏振方向的吸收 .TM偏振方向的吸收是由偏离布里渊带中心的载流子的跃迁所造成的 .

In this paper,the mechanism of photo induced intersubband absorption (PIA) in SiGe multiple quantum wells (QWs) is discussed PIA in the valence band of Si/SiGe QWs is investigated Carriers are optically generated in the QWs using an argon ion laser The resulting infrared absorption is probed with a step scan Fourier transform infrared spectrometer The photo induced infrared absorption in SiGe quantum wells is dominated by two contributions:the free carrier absorption,which is similar to bulk absorption in a uniformly doped SiGe layer,and the valence intersubband absorption in the QWs Both TM and TE polarized intersubband absorptions are measured The TE polarized intersubband absorptions process is attributed to carriers away from the Brillouin zone center Result show that the photo induced technique is appropriate to study valence band mixing effects and their influence on intersubband absorption