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首页> 外文学位 >PICOSECOND AND STEADY-STATE SPECTROSCOPY OF THE WURTZITE SEMIMAGNETIC SEMICONDUCTOR CADMIUM(1-X)MANGANESE(X)SELENIDE (ENERGY RELAXATION, SPIN).
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PICOSECOND AND STEADY-STATE SPECTROSCOPY OF THE WURTZITE SEMIMAGNETIC SEMICONDUCTOR CADMIUM(1-X)MANGANESE(X)SELENIDE (ENERGY RELAXATION, SPIN).

机译：纤锌矿型半导电镉（1-X）锰（X）硒化物的稳态和稳态光谱（能量弛豫，自旋）。

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摘要

The kinetics of a non-equilibrium photogenerated electron-hole plasma in CdSE is investigated using picosecond time resolved spectroscopy at room temperature. Based on the fact that the polar optical phonon emission rate is reduced due to screening by the high density of e-h plasma, the remaining dominant mechanism for hot carrier cooling is the non-polar optical phonon emission even though CdSE is a highly polar semiconductor. Rapid plasma expansion has been proposed as a possible explanation for much lower estimated carrier densities on the grounds of the observed larger spatial width of the photoluminescence relative to the laser spatial width, moderate change of Auger recombination rate with the excitation fluence, the absence of an observed change in the Fermi level with increased excitation intensity and earlier formation of excitons after the picosecond pulse (5 psec) excitation at a low temperature (12K). Large values of the diffusion constant are explained in terms of a screened electron-phonon interaction.; Picosecond time resolved spin relaxation kinetics of high density free carriers is investigated at low temperatures in CdSe (x = 0) and in the dilute semimagnetic semiconductor Cd(,1-x)Mn(,x)Se for x = 0.05 and 0.10. The fast spin relaxation observed in CdSe results from a mechanism associated with the noncentrosymmetric character of the band structure of this material. The spin relaxation times are <20 psec in Cd(,1-x)Mn(,x)Se and are consistent with spin flip Raman scattering measurements. The increase in spin relaxation rate relative to CdSe is explained in terms of the spin exchange between the carriers and the magnetic spin sites.; Using steady state photoluminescence from Cd(,1-x)Mn(,x)Se (0 (LESSTHEQ) x (LESSTHEQ) 0.86), we were able to measure the optical deformation potentials of the conduction band (0.5 x 10('9) eV/cm) and valence band (0.24 x 10('9) eV/cm) in CdSe. The temperature dependent additional bound excitonic binding energy was attributed to the formation of a bound magnetic polaron (h-BMP) at low temperature. The h-BMP formation times are (TURN)340 psec in Cd(,0.95)Mn(,0.05)Se and (TURN)90 psec in Cd(,0.9)Mn(,0.1)Se. These times corresponding to the formation of the BMP from the bound excitons which themselves are formed (TURN)185 psec after the picosecond excitation pulse.
机译：使用皮秒时间分辨光谱在室温下研究了CdSE中非平衡光生电子空穴等离子体的动力学。基于e-h等离子体的高密度屏蔽导致极性光学声子发射速率降低的事实，即使CdSE是高极性半导体，热载流子冷却的其余主要机理是非极性光学声子发射。已经提出快速等离子体膨胀作为可能的解释，因为观察到的较大的光致发光空间宽度相对于激光空间宽度为基础，因此估计的载流子密度要低得多，俄歇复合率随激发通量的变化适中，并且不存在激发能。观察到在低温（12K）皮秒脉冲（5 ps）激发后，费米能级随激发强度的增加和激子的早期形成而变化。用屏蔽的电子-声子相互作用来解释大的扩散常数。在低温下，在CdSe（x = 0）和稀半磁半导体Cd（，1-x）Mn（，x）Se中，对于x = 0.05和0.10，研究了皮秒级高密度自由载流子的自旋弛豫动力学。在CdSe中观察到的快速自旋弛豫是由与该材料的能带结构的非中心对称特征相关的机制引起的。 Cd（，1-x）Mn（，x）Se中的自旋弛豫时间小于20皮秒，与自旋翻转拉曼散射测量结果一致。相对于CdSe的自旋弛豫速率的增加是通过载流子和磁性自旋位点之间的自旋交换来解释的。使用Cd（，1-x）Mn（，x）Se（0（LESSTHEQ）x（LESSTHEQ）0.86）的稳态光致发光，我们能够测量导带的光学形变电势（0.5 x 10（'9 ）eV / cm）和CdSe中的价带（0.24 x 10（'9）eV / cm）。与温度有关的附加的束缚激子结合能归因于在低温下形成的束缚磁极化子（h-BMP）。 h-BMP形成时间在Cd（，0.95）Mn（，0.05）Se中为（TURN）340 psec，在Cd（，0.9）Mn（，0.1）Se中为（TURN）90 psec。这些时间对应于由结合的激子形成BMP，其本身在皮秒激发脉冲后形成（TURN）185 ps。

著录项

  • 作者

    JUNNARKAR, MAHESH R.;

  • 作者单位

    City University of New York.;

  • 授予单位 City University of New York.;
  • 学科 Physics Condensed Matter.
  • 学位 Ph.D.
  • 年度 1986
  • 页码 304 p.
  • 总页数 304
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 O49;
  • 关键词

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