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首页> 外文学位 >Resonant Raman, photoluminescence, and modulation spectroscopy of elemental and II-VI semiconductors.
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Resonant Raman, photoluminescence, and modulation spectroscopy of elemental and II-VI semiconductors.

机译：元素半导体和II-VI半导体的共振拉曼光谱，光致发光光谱和调制光谱。

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摘要

Resonant enhancement enables the discovery and delineation of spin flip Raman scattering (SFRS) from free or donor-bound electrons in diluted magnetic semiconductors (DMSs) containing 3d transition metal ions (TMIs) at doping concentrations. In such studies, the intrinsic g-factor of the host, CdTe in the present case, has to be accounted for accurately. The SFRS in CdTe yields the conduction band electron g-factor of -1.676 +/- 0.007 and displays two resonance peaks mediated by free and donor-bound excitons, respectively. Excitonic signature in modulated reflectivity signals the successful formation of Cd1-xVxTe as an alloy, whereas magnetization measurements show vanadium ions incorporated as V2+ with x ∼ 4 x 10-4 . SFRS of Cd1-xV xTe displays vanadium-related SFRS shifts of a sign opposite to that of the host. This indicates a ferromagnetic s-d exchange interaction between the s-like conduction electrons and the 3d-shell of V2+ in Cd1-xVxTe; from the linear dependence of the s-d exchange energy as a function of magnetization, alpha N0 the s-d exchange constant, is deduced to be (285 +/- 8) meV.; The Van Vleck paramagnetism of Cd1-xFe xTe, a diluted magnetic semiconductor, is explored with electronic Raman spectroscopy of an internal transition of Fe2+, on the one hand, and the spin flip Raman scattering (SFRS) from donor-bound electrons, on the other. Zeeman splitting of the Raman transition from the nonmagnetic ground state to the first excited state displays patterns consistent with energy levels responsible for the Van Vleck paramagnetism. SFRS, in turn, delineates characteristic features of the Van Vleck magnetization, as expected from s-d exchange interaction. The combination of SFRS and magnetization measurements yielded the s-d exchange constant in Cd1-xFe xTe, alphaN0 = (244 +/- 10) meV.; Photoluminescence and wavelength-modulated transmission spectra displaying phonon-assisted indirect excitonic transitions in isotopically enriched 28Si, 29Si, 30Si, as well as in natural Si, have yielded the isotopic mass (M) dependence of the indirect excitonic gap (Egx) and the relevant phonon frequencies. Interpreting these measurements on the basis of a phenomenological theory for (∂Egx/∂M), we deduce Egx(M = infinity) = (1213.8 +/- 1.2) meV, the purely electronic value in the absence of electron-phonon interaction and volume changes associated with anharmonicity. Isotopic mass dependence of the E'0 and E1 direct excitonic gaps is investigated by photo-modulated reflectivity, yielding corresponding values of zero-point renormalizations (64 +/- 4) meV and (129 +/- 10) meV.; The isotopic mass dependence of the A, B, and C excitonic band gaps of ZnO is investigated at liquid helium temperature exploiting wavelength-modulated reflectivity. The observed dependence is analyzed in terms of the zero-point renormalization of the band gap by electron-phonon interaction and the dependence of volume on isotopic mass. The analysis yields zero-point renormalizations by electron-phonon interaction 152 +/- 20 meV (A), 146 +/- 26 meV (B), and 158 +/- 21 meV (C). The temperature dependence of the band gaps is studied in specimens having natural isotopic abundance with electro-, photo-, and wavelength-modulation reflectivity in the range 10-402 K. Zero-point renormalizations of the band gaps by electron-phonon interaction 184.6 meV (A), 163.6 meV (B), and 179.6 meV (C) are deduced from fits to the temperature data generated by the two-oscillator model.
机译：共振增强可从掺杂浓度为3d过渡金属离子（TMI）的稀释磁性半导体（DMS）中的自由电子或施主结合电子中发现和描述自旋翻转拉曼散射（SFRS）。在此类研究中，必须准确计算宿主的固有g因子CdTe（在当前情况下）。 CdTe中的SFRS产生的导带电子g因子为-1.676 +/- 0.007，并分别显示出由游离和供体结合的激子介导的两个共振峰。调制反射率中的激子信号表示成功形成了Cd1-xVxTe作为合金，而磁化强度测量结果显示钒离子以V 2+的形式掺入x〜4 x 10-4。 Cd1-xV xTe的SFRS显示与钒有关的SFRS位移，其符号与主体的符号相反。这表明Cd1-xVxTe中s型传导电子和V2 +的3d壳之间存在铁磁s-d交换相互作用。根据s-d交换能量与磁化强度的线性关系，将s-d交换常数αN0推导为（285 +/- 8）meV。一方面，利用电子拉曼光谱法研究了Fe2 +的内部跃迁，另一方面利用供体结合电子的自旋翻转拉曼散射（SFRS）探索了稀释的磁性半导体Cd1-xFe xTe的Van Vleck顺磁性。其他。从非磁性基态到第一激发态的拉曼跃迁的塞曼分裂显示出与负责Van Vleck顺磁性的能级一致的模式。 SFRS依次描绘了s-d交换相互作用所期望的Van Vleck磁化特征。 SFRS和磁化测量的组合产生Cd1-xFe xTe的s-d交换常数，alphaN0 =（244 +/- 10）meV。在同位素富集的28Si，29Si，30Si以及天然Si中，显示声子辅助间接激子跃迁的光致发光和波长调制透射光谱已得出间接激子间隙（Egx）的同位素质量（M）依赖性以及相关的声子频率。根据（∂Egx/∂M）的现象学理论解释这些测量结果，我们推导出Egx（M =无穷大）=（1213.8 +/- 1.2）meV，这是在没有电子-声子相互作用和与非谐性相关的音量变化。通过光调制反射率研究E'0和E1直接激子间隙的同位素质量依赖性，得出相应的零点重归一化值（64 +/- 4）meV和（129 +/- 10）meV。利用波长调制反射率研究了液氦温度下ZnO的A，B和C激子带隙的同位素质量依赖性。根据电子声子相互作用对带隙的零点重新归一化以及体积对同位素质量的依赖性，对观察到的依赖性进行了分析。该分析通过电子声子相互作用152 +/- 20 meV（A），146 +/- 26 meV（B）和158 +/- 21 meV（C）产生零点重新归一化。在具有自然同位素丰度且电，光和波长调制反射率在10-402 K范围内的标本中研究了带隙的温度依赖性。通过电子-声子相互作用，带隙的零点重新归一化184.6 meV （A），163.6 meV（B）和179.6 meV（C）是通过对两个振荡器模型生成的温度数据进行拟合得出的。

著录项

  • 作者

    Tsoi, Stanislav.;

  • 作者单位

    Purdue University.;

  • 授予单位 Purdue University.;
  • 学科 Physics Condensed Matter.
  • 学位 Ph.D.
  • 年度 2005
  • 页码 152 p.
  • 总页数 152
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 O49;
  • 关键词

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