Quantitative Raman Spectrum and Reliable Thickness Identification for Atomic Layers on Insulating Substrates

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• 作者：Song-Lin Li ; Hisao Miyazaki ; Haisheng Song ; Hiromi Kuramochi ; Shu Nakaharai ; Kazuhito Tsukagoshi
• 刊名：ACS Nano
• 出版年：2012
• 出版时间：August 28, 2012
• 年：2012
• 卷：6
• 期：8
• 页码：7381-7388
• 全文大小：576K
• 年卷期：v.6,no.8(August 28, 2012)
• ISSN：1936-086X

文摘

We demonstrate the possibility in quantifying the Raman intensities for both specimen and substrate layers in a common stacked experimental configuration and, consequently, propose a general and rapid thickness identification technique for atomic-scale layers on dielectric substrates. Unprecedentedly wide-range Raman data for atomically flat MoS₂ flakes are collected to compare with theoretical models. We reveal that all intensity features can be accurately captured when including optical interference effect. Surprisingly, we find that even freely suspended chalcogenide few-layer flakes have a stronger Raman response than that from the bulk phase. Importantly, despite the oscillating intensity of specimen spectrum versus thickness, the substrate weighted spectral intensity becomes monotonic. Combined with its sensitivity to specimen thickness, we suggest this quantity can be used to rapidly determine the accurate thickness for atomic layers.

Keywords:

nanomaterial; atomic layer; Raman enhancement; characterization