Acoustic waves in finite superlattices: Influence of buffer layers
Acoustic waves in finite superlattices: Influence of buffer layers
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DOI：
10.1103/physrevb.59.1999
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发表时间：
1999-01-15
影响因子：
3.7
通讯作者：
Dobrzynski, L
中科院分区：
文献类型：
--
作者：
Hammouchi, M;El Boudouti, EH;Dobrzynski, L
本文从理论上研究了有限超晶格中缓冲层对剪切水平极化声波的影响。使用绿色的函数方法，我们得到了封闭形式的表达的局部和总的状态密度的频率ω和波矢量k（平行于）平行于层的函数。我们还导出了声子俘获时间的表达式，并与态密度进行了比较。由于衬底/缓冲层/超晶格的相互作用，发现了不同类型的局域和共振分立模，并研究了它们的性质。特别是，我们发现定义良好的导模在缓冲层或超晶格中取决于缓冲区中的横向声波的速度是低于或高于那些在超晶格和衬底，分别的可能性。这些模式表现为状态密度和捕获时间的明确峰值。本文给出了我们的分析结果的具体应用的GaAs（Si）缓冲层嵌入之间的Si（GaAs）衬底和有限的GaAs-AlAs超晶格。[S0163-1829（99）13003-0]。
The influence of buffer layers on acoustic waves of shear horizontal polarization in finite superlattices is investigated here theoretically. Using a Green's-function method, we have obtained closed-form expressions of local and total densities of states as a function of the frequency omega and the wave vector k(parallel to) parallel to the layers. The expressions of the phonon trapping times are also derived and compared to the density of states. Due to the substrate/buffer layer/superlattice interaction, different kind's of localized and resonant discrete modes are found and their properties are investigated. In particular, we show the possibility of finding well-defined guided modes in the buffer layer or in the superlattice depending on whether the velocity of the transverse acoustic waves in the buffer is lower or higher than those in the superlattice and the substrate, respectively. These modes appear as well-defined peaks of the density of states and trapping times. Specific applications of our analytical results are given in this paper for a GaAs (Si) buffer layer embedded between a Si (GaAs) substrate and a finite GaAs-AlAs superlattice. [S0163-1829(99)13003-0].