First-Principles Prediction of Optical Absorption Enhancement for Si Native Defect Clusters under Biaxial Strain
First-Principles Prediction of Optical Absorption Enhancement for Si Native Defect Clusters under Biaxial Strain
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DOI：
10.1149/1.3511714
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发表时间：
2011
影响因子：
--
通讯作者：
R. Bondi;Sangheon Lee;G. Hwang
中科院分区：
文献类型：
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作者：
R. Bondi;Sangheon Lee;G. Hwang
我们利用密度泛函理论计算定性地探讨了在双轴应变= 3、0和3%的条件下，四配位空位V4和间隙I4团簇对晶体Si -Si光吸收光谱的影响。虽然两种天然缺陷簇都通过红移吸收边来增强c-Si的吸收，但我们观察到双轴应变对c-Si的吸收有额外的增强。应变大小的增大有增强吸收效果的趋势，但应变的最佳符号呈现互补关系：压缩应变最有效地增强V4吸收，而拉伸应变最有效地增强I4吸收。吸收红移作为应变的函数与有效的带隙减小有很好的相关性，包括在一定条件下出现中间带= 3和V4为0%。我们的研究结果表明，对天然缺陷分布及其应变场的操纵可以用来设计Si吸收光谱。
We use density-functional theory calculations to qualitatively explore the effects of fourfold-coordinated vacancy V4 and interstitial I4 clusters on optical absorption spectra in crystalline Si c-Si under selected conditions of biaxial strain =� 3, 0, and 3%. While both native defect clusters enhance c-Si absorption by redshifting the absorption edge, we observe additional enhancement from biaxial strain. Increased strain magnitude tends to increase the absorption enhancement effect, but the optimal sign of strain exhibits a complementary relationship: compressive strain most effectively enhances V4 absorption, while tensile strain most effectively enhances I4 absorption. The absorption redshift as a function of strain correlates well with effective bandgap reduction, including the appearance of an intermediate band under certain conditions = �3 and 0% for V4. Our results suggest that manipulation of native defect distributions and their strain fields can be used to engineer the Si absorption spectra.