【作者】 何晓勇；

【导师】 封松林； 曹俊诚；

【作者基本信息】 中国科学院研究生院（上海微系统与信息技术研究所） ， 微电子学与固体电子学， 2007， 博士

【摘要】 半导体太赫兹(THz)量子级联激光器(QCL)是一种重要的THz辐射源，THz波导传输对THz技术的发展也非常重要。本文主要研究了THz QCL的电子输运和波导特性，探索了THz金属丝波导的传输机理。研究结果对理解THz QCL中载流子的散射机制和波导特性，优化THz QCL设计有重要意义。本文的主要研究内容和结论如下：1．研究了THz QCL中电子-LO声子(受限制声子和界面声子)、电子-电子和电子-离化杂质等相互作用的散射率，并计算了温度和掺杂浓度等因素对散射率的影响。结果表明，LO声子散射和电子-电子散射是THz QCL的主要散射机制，在量子阱较宽的情况下，受限制声子的散射率可以与界面声子的散射率相比，在计算过程中应考虑到受限制声子的贡献。2．采用二维有限元方法研究了THz QCL的波导特性。结果表明，随着有源区掺杂浓度的提高，波导损耗增加，阈值电流增加，波导限制因子降低。双面金属波导具有良好的光模限制作用，限制因子较单面金属波导有明显提高，导热性良好。随着波长增加双面金属波导的优点更加突出。3．通过求解THz传播模的特征值方程研究了THz金属丝波导的传输特性。结果表明，随着频率增加，金属丝波导的群速度降低，损耗增加；随着金属丝半径增加，金属丝波导群速度和损耗降低。采用高介电常数的金属可提高金属丝波导的传输性能。改变金属丝表面包覆层的厚度可很好地调制金属丝波导的传输特性。更多还原

【Abstract】 Terahertz (THz) quantum cascade lasers (QCL) is an important kind of semiconductor radiation sources. THz waveguide propagation is also very important in the development of THz technology. In this dissertation, we study the electron transport in THz QCL, compare and discuss the waveguide property, and investigate the propagation property of THz metal wire waveguide. The result is very helpful to understand the physical mechanism and waveguide property of THz QCL. The main conclusions are as follows:1. The scattering mechanisms in THz QCL, such as electron-LO phonon scattering and electron-electron scattering have been investigated. The results show that LO phonon scattering and electron-electron scattering are probably the main scattering mechanisms in THz QCL. If the quantum well is wide, the scattering rates by confined phonons is comparable to that by interface phonons and should be taken into consideration in the calculation.2. The main waveguide design methods of THz QCL have been given and discussed by using two dimensional finite element methods. The results indicate that metal-metal waveguide has high optical confinement, low confinement factor, and small waveguide width. The doping concentration in the active region has great effect on the waveguide property. With the increasing of doping concentration, the waveguide loss, threshold gain and current density of THz QCL increase, the confinement factor decrease.3. The propagation property of THz metal wire waveguide has been investigated by numerically solving the complex eigenvalue equation. It is shown that the group velocity decreases as frequency increase, while attenuation amplitude increases with the frequency. With the increasing of metal wire radius, the group velocity and attenuation amplitude decrease. The TM mode field exponentially decreases from the interface into metal and air, respectively. In addition, the metal wire waveguide property could be modified by changing the thickness of coating layer.更多还原