【作者】 于晓龙；

【导师】 班士良；

【作者基本信息】 内蒙古大学 ， 理论物理， 2005， 硕士

【摘要】 本文利用Larsen等人改进的微扰方法,考虑实际异质结势,计及体纵光学声子、两支界面光学声子的影响,从理论上讨论磁场下半导体异质结中极化子朗道能级的基态和第一激发态的能量,获得极化子行为对外磁场的依赖关系,并分弱、强磁场和回旋共振三种情况讨论极化子回旋质量及其压力效应。对Ⅲ—Ⅴ族GaAs/AlAs半导体异质结的计算结果显示:在弱场极限,尽管体纵光学声子对极化子回旋质量的影响更为重要,但高频支光学声子的贡献是不容忽略的;随着磁场的增加,两支界面声子的贡献逐渐变为与体纵光学声子的贡献相比拟。压力下(40Kbar),两支界面声子对极化子回旋质量的贡献随着磁场强度的增加愈加显著,体声子和界面声子的贡献均为重要。强场下,各支声子对极化子回旋质量贡献随场强的变化性质及其压力效应与弱场时随磁场减弱的变化性质相同,但符号相反。在各支声子频率附近发生回旋共振时,极化子回旋质量的压力效应均为显著。在以后的工作中,特别是讨论极化子回旋共振的压力效应时,应该采用精细的界面声子模。 为了在三元混晶中对回旋质量等相关参数做进一步研究,本文采用班士良等人的简化相干势近似(SCPA)方法,对Ⅲ—Ⅴ族宽禁带含氮三元混晶InGaN半导体的禁带宽度进行了计算,与实验符合较好。结果表明:SCPA是一可取的近似方法。更多还原

【Abstract】 Considering a realistic interface potential, a perturbation method improved by Larsen et al has been adopted to study polarons in semiconductor heteroj unctions in a magnetic field taking into account of the interaction between an electron and both of bulk longitudinal-optical (LO) and the two branches of interface-optical (10) phonons. The relation of polaron properties dependent on external magnetic fields is obtained by discussing the polaron energies of ground states and the first excited states of Landau levels. The polaron cyclotron mass (PCM) and pressure effect are studied for weak, strong and resonant magnetic fields, respectively. The numerical results for semiconductor heteroj unctions consisting of III-V group show that the contribution from 10 phonons with higher frequency can not be neglected in weak field limit, although the bulk LO phonons are more important to influence on the PCM. As increase of a magnetic field, the contribution from the two branches of 10 phonons tends to be comparable with that from the bulk LO phonons. It becomes more and more important that the contribution to the PCM from the two branches of 10 phonons as the magnetic field increases under pressure of 40Kbar. At the same time, both of the contributions from bulk LO and 10 phonons are important. The properties of the contributions to the PCM from different branches of phonons varying with strong magnetic fields and their pressure effect are the same and negative with that for weak magnetic fields. The pressure effect of LO and 10 phonons on the PCM are important when the cyclotron resonance happens near the frequencies of different branches of phonons. The detailed 10 phonon modes should be considered in the future work especially when ones study the pressure effects of cyclotron resonance of polarons.For the further work to study the relative coefficients such as PCM in ternary mixedsemiconductors (TMC), a simple coherent potential approximation (SCPA) proposed by Ban et al is adopted to calculate the band gap for nitrided TMC semiconductor InGaN with wide gap of III-V group. The result obtained is in better agreement with experiments to show the SCPA is an acceptable approximation.更多还原