arXiv subjects

Andrey V. Krayev

Publications and source records attributed to Andrey V. Krayev.

2 recordsLinked to original sources

arXiv2021

Nanoscale Raman Characterization of a 2D Semiconductor Lateral Heterostructure Interface

The nature of the interface in lateral heterostructures of 2D monolayer semiconductors including its composition, size, and heterogeneity critically impacts the functionalities it engenders on the 2D system for next-generation optoelectronics. Here, we use tip-enhanced Raman scattering (TERS) to characterize the interface in a single-layer MoS2/WS2 lateral heterostructure with a spatial resolution of 50 nm. Resonant and non-resonant TERS spectroscopies reveal that the interface is alloyed with a size that varies over an order of magnitude-from 50-600 nm-within a single crystallite. Nanoscale imaging of the continuous interfacial evolution of the resonant and non-resonant Raman spectra enables the deconvolution of defect-activation, resonant enhancement, and material composition for several vibrational modes in single-layer MoS2, MoxW1-xS2, and WS2. The results demonstrate the capabilities of nanoscale TERS spectroscopy to elucidate macroscopic structure-property relationships in 2D materials and to characterize lateral interfaces of 2D systems on length scales that are imperative for devices.

physics.app-ph↗

arXiv2020

Fingerprints of the Strong Interaction between Monolayer MoS2 and Gold

Gold-mediated exfoliation of MoS2 has attracted considerable interest in the recent years. A strong interaction between MoS2 and Au facilitates preferential production of centimeter-sized monolayer MoS2 with near-unity yield and provides a heterostructure system noteworthy from a fundamental standpoint. However, little is known about the detailed nature of the MoS2-Au interaction and its evolution with the MoS2 thickness. Here, we identify specific vibrational and binding energy fingerprints of such strong interaction using Raman and X-ray photoelectron spectroscopy, which indicate substantial strain and charge-transfer in monolayer MoS2. Near-field tip-enhanced Raman spectroscopy reveals heterogeneity of the MoS2-Au interaction at the nanoscale, reflecting the spatial non-conformity between the two materials. Far-field micro-Raman spectroscopy shows that this interaction is strongly affected by the roughness and cleanliness of the underlying Au. Our results elucidate the nature of the strong MoS2-Au interaction and provide guidance for strain and charge doping engineering of MoS2.

cond-mat.mtrl-sci↗