Berdekas D, Ves S
Direction of High Schools Education of Larissa, Lykeio of Giannouli, GR-41500 Larissa, Greece.
J Phys Condens Matter. 2009 Jul 8;21(27):275405. doi: 10.1088/0953-8984/21/27/275405. Epub 2009 Jun 10.
The lattice dynamics of (GaAs)(n)/(AlAs)(n)(001) superlattices (SLs), n = 1,2, with perfect and disordered (non-perfect) interfaces is studied in detail. The SLs with disordered interfaces are approached by primitive cells, much larger in volume than that of the perfect SL primitive cell. The dynamical matrices of the SLs have been constructed from a combination of the dynamical matrices corresponding to the bulk crystalline constituents, while the interionic forces are calculated by using a ten-parameter valence overlap shell model (VOSM). Furthermore, we calculate the Raman spectra, for both perfect and disordered superlattices by using an eight-parameter bond polarizability model (BPM). Our theoretical results are in very good agreement with the available experimental spectra. Finally, our results clearly demonstrate that intermixing of Ga and Al cations, even to a very small extent, can induce Raman activity, which although not expected in the spectra of perfect superlattices, is actually observed experimentally.
详细研究了n = 1、2时具有完美和无序（非完美）界面的(GaAs)(n)/(AlAs)(n)(001)超晶格（SLs）的晶格动力学。具有无序界面的超晶格由原胞来描述，其体积比完美超晶格原胞的体积大得多。超晶格的动力学矩阵是由对应于体晶组成部分的动力学矩阵组合而成的，而离子间力则通过使用十参数价重叠壳层模型（VOSM）来计算。此外，我们使用八参数键极化率模型（BPM）计算了完美和无序超晶格的拉曼光谱。我们的理论结果与现有的实验光谱非常吻合。最后，我们的结果清楚地表明，即使Ga和Al阳离子的混合程度非常小，也会诱导拉曼活性，这在完美超晶格的光谱中虽然未被预期，但实际上在实验中被观察到了。
