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arXiv 0908.1378cond-mat.mes-hallcond-mat.mtrl-sciphysics.optics
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互扩散和量子限制对Ge/Si(100)量子点异质结构拉曼光谱的影响

Effect of interdiffusion and quantum confinement on Raman spectra of the Ge/Si(100) heterostructures with quantum dots

I. V. Kucherenko, V. S. Vinogradov, N. N. Melnik, L. V. Arapkina, V. A. Chapnin, K. V. Chizh, V. A. Yuryev

摘要:

利用拉曼散射研究了分子束外延生长的自组织Ge/Si量子点的声子模。结果表明,在{λ}3价带和{λ}1导带(跃迁E1和E1+{Delta}1)之间的激子激发下,Ge-Ge和Si-Ge振动模显著增强,这使得可以从极小体积的Ge,甚至从一层厚度为~ 10 A的量子点中观察到拉曼散射光谱。结果表明,Si从Si间隔层扩散到Ge量子点中形成Ge_ xSi_{1-x}固溶体,并估算了Si的浓度。结果表明,由于声子尺寸限制效应,Ge-Ge模的频率随Ge层厚度从10埃减小到6埃而减小10 1/cm。

英文摘要:

We used Raman scattering for study the phonon modes of self-organized Ge/Si quantum dots, grown by a molecular-beam epitaxy method. It is revealed, that Ge-Ge and Si-Ge vibrational modes considerably intensify at excitation of exciton between the {Lambda}3 valence and {Lanbda}1 conduction bands (transitions E1 and E1+{Delta}1), that allows to observe Raman scattering spectrum from extremely small volumes of Ge, even from one layer of quantum dots with the layer thickness of ~ 10 A. It is shown that Si diffuses into the Ge quantum dots from the Si spacer layers forming Ge_xSi_{1-x} solid solution, and Si concentration was estimated. It is revealed, that the frequency of Ge-Ge mode decreases in 10 1/cm at decreasing of the Ge layer thickness from 10 up to 6 A as a result of phonon size confinement effect.

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