Study of InN nano-stmcture with semiconducting and superconducting properties

以下是根据2002年9月提交的提案进行的研究总结。通过与独立行政机构通信研究实验室的higashiwaki博士的合作，我们成功地培养出了载流子浓度从2×10^<18>cm^<-3>到1.5×10^<19>cm^<-3>，迁移率为1600 cm^2V^<-1>s^<-1>的掺硅InN。这些样品在0.5 K以下未显示任何电阻率异常。然而，当载流子浓度小于5×10^<18>cm^<-3>时，样品显示出明显的舒布尼科夫-德哈斯振荡。通过对外加磁场与晶体c轴夹角依赖性的舒布尼科夫-德哈斯振荡的分析，我们得出了InN的电子结构由两部分组成；一种是球面三维分布的费米曲面。另一个是在a-b平面上一维展开的。在2003年奈良举行的国际氮化物半导体会议上报道了I…More nN的电子结构。通过拉曼散射和FfIR测量研究了自由载流子与LO声子相互作用对载流子浓度的依赖关系。si掺杂后载流子浓度从1.8×10^<18>到1.5×10^<19>cm^<-3>。在a-b平面的振动作用下，红外反射光谱揭示了E_1（LO）声子与自由载流子的等离子体振荡之间的线性耦合。从等离子体频率估计电子的有效质量为m^*_e=0.085 m_o。沿c轴的振动作用下的拉曼光谱表明，A_1（LO）声子与自由载流子非线性耦合，其中区中心LO声子与沿c轴的准连续态电子态之间的Fano干扰较为突出。利用这些结果，讨论了InN的各向各向的电子结构，讨论了InN的超导性与杂质的关系。我们给出了MBE在蓝宝石（0001）表面生长的InN的吸收、发光和拉曼光谱对载流子浓度的依赖关系，在载流子浓度区观察到超导性，载流子浓度由2×l0^<19>cm^<-3>改变为7×10^<20>cm^<-3>。带隙能量随载流子浓度的增加而增加，但发光峰保持在0.8 eM左右，A_1（LO）声子处的Fano共振随载流子浓度的增加而增强。存在使InN产生超导性的最佳载流子浓度区域。少

The followings are the summary of research conducted based on the proposal submitted on September 2002.[1]Observation of Shubnlkov-da Haas measurements of Si-doped InNWith the collaboration with Dr.Higashiwaki of Communications Research Laboratory of Independent Administrative Institution, we succeeded to grow Si-doped InN with the carrier concentration from 2×10^<18>cm^<-3> to 1.5×10^<19>cm^<-3> and the mobility of 1600 cm^2V^<-1>s^<-1>. These samples did not show any resistivity anomaly down to 0.5 K. The samples, however show clear Shubnikov-de Haas oscillations when the carrier concentration is less than 5×10^<18>cm^<-3>. From the analysis of the Shubnikov-de Haas oscillation of angle dependence between the applied magnetic field and crystal c axis, we concluded that the electronic structure of InN consists of two components ; one is the Fermi surface with spherical 3-dimensional distribution. The other is the one spread one dimensionally on a-b plane. The electronic structure of I … More nN was reported 5^<th> International Conference of Nitride Semiconductors held at Nara 2003.[2]Optical properties of Si-doped InNCarrier concentration dependence of the interaction between free carriers and LO phonons of InN is studied by Raman scattering and FfIR measurements The carrier concentration is varied from 1.8×10^<18> to 1.5×10^<19>cm^<-3> by Si-doping. The infrared reflection spectra, to which the vibration in the a-b plane contributes, reveal linear-coupling between the E_1(LO) phonon and the plasma oscillation of the free carriers. From the plasma frequency the electron effective mass is estimated to be m^*_e=0.085 m_o for the intrinsic InN. The Raman spectra, to which the vibration along the c-axis contributes, reveal that the A_1(LO) phonon and free carriers couple non-linearly, where Fano interference between the zone-center LO phonon and the quasicontinuum electronic state along the c-axis is prominent. With these results, the anisotropic electronic structure of InN was discussed[3]The relationship between the superconductivity and impurities of InNWe present the carrier concentration dependence of the absorption, luminescence and Raman spectra of InN grown by MBE on sapphire (0001) surface in the carrier concentration region where superconductivity was observed The carrier concentration was changed from 2×l0^<19>cm^<-3> to 7×10^<20>cm^<-3> by Mg and Dy impurities. The band gap energy increased as the concentration increased, but the luminescence peak remained at around 0.8 eM The Fano resonance observed at the A_1(LO) phonon became stronger when the carrier concentration increased. There was an optimum carrier concentration region for the superconductivity of InN to occur.. Less