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Updated: Jan 14, 2026

Comprehensive Characterization of Extended Defects in Semiconductor Materials by a Scanning Electron Microscope
Published on: May 28, 2016
Geometrical and vibrational properties of the defects driving the boson peak
Shivam Mahajan1, Darryl Seow Yang Han1, Cunyuan Jiang2,3,4
1Nanyang Technological University, Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Singapore.
Abstract:
In amorphous solids, the vibrational density of states shows an excess of modes over the Debye model, known as the boson peak, whose origin remains unclear. Studies suggest a link to quasi-localized nonphononic vibrations or "defects," but identifying them is challenging due to hybridization with phonons that renders methods based on localization properties, such as the participation ratio, unreliable. We introduce a practical method to separate hybridized phonons from localized vibrations and find that boson peak phonons hybridize with compact, two-dimensional defects exhibiting oscillatory pure shear deformations. These two-dimensional defects are also exposed by the procedure recently employed to identify stringlets (Y.-C. Hu et al. [Nat. Phys. 18, 669 (2022)1745-247310.1038/s41567-022-01628-6]), suggesting that these may not be one-dimensional objects as speculated. Our work demonstrates the presence of localized defects at the boson peak frequency and provides a comprehensive characterization of their vibrational and geometric properties, resolving the tension between the concepts of quasi-localized quadrupolar defects and stringlets.
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