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本文详细地研究了原始生长和退火处理后的Si/Ge量子点的拉曼光谱。我们观测到了Si/Ge量子点的一系列本征的拉曼振动模以及Ge-Ge模的LO和TO声子峰间4.2cm-1的频率劈裂。通过这些参数,我们自洽地确定了原始生长的平面直径为20nm和高为2nm的Si/Ge量子点内Ge的平均组分为80%,平均应变为-3.4%。分析清楚地表明了这种小尺寸的Si/Ge量子点内的应变仍遵从双轴应变,并且应变的释放主要由量子点和Si隔离层间Si-Ge原子互扩散决定。
In this paper, the Raman spectra of Si / Ge QDs after primary growth and annealing have been studied in detail. We observed a series of intrinsic Raman modes of Si / Ge quantum dots and a frequency splitting of 4.2 cm-1 between the LO and TO phonon peaks of the Ge-Ge mode. Through these parameters, we have consistently determined that the average composition of Ge in Si / Ge QDs with the original growth of 20nm in diameter and 2nm in height is 80% and the average strain is -3.4%. The analysis clearly shows that the strain in this small size Si / Ge quantum dot still follows the biaxial strain and the strain release is mainly determined by the interdiffusion of the Si-Ge atoms between the quantum dots and the Si isolation layer.