Tanwar Manushree, Pathak Devesh K, Chaudhary Anjali, Krylov Alexander S, Pfnür Herbert, Sharma Ashutosh, Ahn Byungmin, Lee Sangyeob, Kumar Rajesh
Materials and Device Laboratory, Discipline of Physics, Indian Institute of Technology Indore, Simrol 453552, India.
Kirensky Institute of Physics, Federal Research Center KSC SB RAS Krasnoyarsk 660036, Russia.
J Phys Chem Lett. 2021 Mar 4;12(8):2044-2051. doi: 10.1021/acs.jpclett.1c00217. Epub 2021 Feb 19.
Quantum size effects on interferons (electron-phonon bound states), confined in fractal silicon (Si) nanostructures (NSs), have been studied by using Raman spectromicroscopy. A paradoxical size dependence of Fano parameters, estimated from Raman spectra, has been observed as a consequence of longitudinal variation of nanocrystallite size along the Si wires leading to local variations in the dopants' density which actually starts governing the Fano coupling, thus liberating the interferons to exhibit the typical quantum size effect. These interferons are more dominated by the effective reduction in dopants' density rather than the quantum confinement effect. Detailed experimental and theoretical Raman line shape analyses have been performed to solve the paradox by establishing that the increasing size effect actually is accompanied by receding Fano coupling due to the weakened electronic continuum. The latter has been validated by observing a consequent variation in the Raman signal from dopants which was found to be consistent with the above conclusion.
利用拉曼光谱显微镜研究了限制在分形硅（Si）纳米结构（NSs）中的干扰素（电子 - 声子束缚态）的量子尺寸效应。从拉曼光谱估计的法诺参数呈现出一种矛盾的尺寸依赖性，这是由于纳米微晶尺寸沿硅线的纵向变化导致掺杂剂密度的局部变化，而这种变化实际上开始主导法诺耦合，从而使干扰素能够展现出典型的量子尺寸效应。这些干扰素更多地受掺杂剂密度有效降低的影响，而非量子限制效应。通过确定尺寸效应的增加实际上伴随着由于电子连续体减弱导致的法诺耦合减弱，进行了详细的实验和理论拉曼线形分析来解决这一矛盾。通过观察到掺杂剂拉曼信号随之发生的变化验证了后者，发现该变化与上述结论一致。
