纤锌矿氮化镓基阶梯量子阱中界面声子的色散谱与散射率  

Dispersive Spectra and Scattering Rates of Interface Optical Phonon Modes in a Wurtzite GaN-Based Step Quantum Well with Strong Built-in Electric Field

作　　者：张立[1] 

机构地区：[1]广州番禺职业技术学院电子技术与材料开发研究所,广州511483

出　　处：《光散射学报》2016年第2期131-139,共9页The Journal of Light Scattering

基　　金：国家自然科学基金项目(60906042;61178003及61475039);广州市创新学术团队项目(13C17);广州市"羊城学者"学术带头人项目(10B010D);广州市教育局科技项目(10B001);广州市番禺区产学项目(2010-D-09-1103004)联合资助

摘　　要：本文理论分析了纤锌矿GaN-基阶梯量子阱中的电子-界面光学声子散射性质。阶梯量子阱中的解析的界面声子态及Frhlich电子-声子相互作用哈密顿被导出了。在考虑强内建电场效应及能带的非抛物性特性的情况下,阶梯量子阱结构精确解析的电子本征态也被给出了。以一个四层纤锌矿AlN-基阶梯量子阱为例进行了数值计算。结果发现,系统中存在四支界面光学声子模,这一观察明显不同于对称的GaN/AlN单量子阱与双量子阱的情况。这一差异被归结为阶梯量子结构的非对称性。GaN-基阶梯量子阱中的子带内散射率与子带间散射率比GaAs-基阶梯量子阱的结果大一个数量级,这被归因于GaN-基晶体大的电子-声子耦合常数。GaN-基阶梯量子阱的子带内散射率表现出与GaAs-基体系类似的结构参数依赖关系,但两类体系的子带间散射率对阶梯量子阱结构参数依赖则明显不同,这被归结为GaN-基阶梯量子阱结构中强的内建电场效应及带的非抛物性。结果还表明,高频界面声子模相对于低频界面声子模,对散射率的贡献更大。Electron-interface optical（IO）phonon scattering rates in a wurtzite GaN-based asymmetrical step quantum well（QW）are theoretically analyzed by using the usual Fermi golden rule.Based on the dielectric continuum model and Loudon＇s uniaxial crystal model,the analytical IO phonon states and their Frhlich electronphonon interaction Hamiltonian are derived.Taking into consideration the effects of strong built-in electric field（BEF）and the band nonparabolicity,the exact electronic eigen-states in the step QW are also obtained with the aid of two Airy functions.Numerical calculations on a wurtzite AlN/GaN/AlxGa1-xN/AlN step QW are performed.It is found that there are four branches of IO phonon modes in the asymmetric nitride step QWs,which is obviously different from the situation of symmetrical GaN/AlN single and coupling QWs.This is mainly ascribed to the asymmetry of the step QW structures studied here.The calculated results show that the intrasubband and intersubband scattering rates in wurtzite step QWs are one order of magnitude larger than those in GaAs-based step QWs,which is attributed to the larger electron-phonon coupling constants of GaN-based materials.The intrasubband scattering rates in wurtzite step QWs behave analogous dependent relation as those in cubic GaAs-based step QWs on the structural parameters,but the intersubband scattering rates here show obviously different dependent behavior on the structural parameters.This is ascribed to the effects of the strongBEF and the band nonparabolicity.Moreover,the high-frequency IO modes play more important role to the total scattering rates than the low-frequency ones.

关 键 词：电子-声子散射率 界面声子模 纤锌矿阶梯量子阱 内建电场 带非抛物性 

分 类 号：O469[理学—凝聚态物理] O482.3[理学—电子物理学]