Phonon Confinement Effect in Two-dimensional Nanocrystallites of Monolayer MoS2 to Probe Phonon Dispersion Trends Away from Brillouin-Zone Center
Phonon Confinement Effect in Two-dimensional Nanocrystallites of Monolayer MoS2 to Probe Phonon Dispersion Trends Away from Brillouin-Zone Center
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单层 MoS2 二维纳米晶中的声子限制效应探测远离布里渊区中心的声子色散趋势
DOI：
10.1088/0256-307x/33/5/057801
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发表时间：
2016-05
影响因子：
3.5
通讯作者：
Tan Ping-Heng
中科院分区：
文献类型：
--
作者：
Shi Wei;Zhang Xin;Li Xiao-Li;Qiao Xiao-Fen;Wu Jiang-Bin;Zhang Jun;Tan Ping-Heng
在纳米晶体中，拉曼过程的基本动量守恒条件q ~ 0被放宽，远离布里渊区中心的声子将参与到拉曼散射中，这被称为纳米晶体中的声子限制效应。这通常在各种NC中给出拉曼峰的下移和不对称加宽。最近，发现1 L MoS 2 NC的A′1模向高频侧显示出蓝移和非对称加宽[Chem. Soc. Rev. 44（2015）2757和Phys. Rev. B 91（2015）195411]。在这项工作中，我们仔细检查这个问题，通过研究拉曼光谱的离子注入技术制备的1 L二硫化钼纳米碳在很宽的范围内的离子注入剂量。由于声子不确定性主要由其畴大小决定，因此1 L MoS 2纳米晶体中的E′和A′1模使用相同的限制系数。A′1和E′模附近的非对称展宽归因于带边缺陷激活声子的出现和两个模的本征非对称展宽，其中声子色散曲线沿着Γ-K和Γ-M的各向异性也被考虑.光致发光光谱证实了离子注入1 L MoS 2中形成了小畴尺寸的1 L MoS 2纳米晶。该研究不仅提供了一种通过纳米颗粒的拉曼散射快速探测二维材料远离Γ的声子色散趋势的方法，而且为全面理解不同纳米材料中不同模式的约束效应提供了参考。
The fundamental momentum conservation requirement q ~ 0 for the Raman process is relaxed in the nanocrystallites (NCs), and phonons away from the Brillouin-zone center will be involved in the Raman scattering, which is well-known as the phonon confinement effect in NCs. This usually gives a downshift and asymmetric broadening of the Raman peak in various NCs. Recently, the A′1 mode of 1L MoS2 NCs is found to exhibit a blue shift and asymmetric broadening toward the high-frequency side [Chem. Soc. Rev. 44 (2015) 2757 and Phys. Rev. B 91 (2015) 195411]. In this work, we carefully check this issue by studying Raman spectra of 1L MoS2 NCs prepared by the ion implantation technique in a wide range of ion-implanted dosage. The same confinement coefficient is used for both E′ and A′1 modes in 1L MoS2 NCs since the phonon uncertainty in an NC is mainly determined by its domain size. The asymmetrical broadening near the A′1 and E′ modes is attributed to the appearance of defect-activated phonons at the zone edge and the intrinsic asymmetrical broadening of the two modes, where the anisotropy of phonon dispersion curves along Γ–K and Γ–M is also considered. The photoluminescence spectra confirm the formation of small domain size of 1L MoS2 nanocrystallites in the ion-implanted 1L MoS2. This study provides not only an approach to quickly probe phonon dispersion trends of 2D materials away from Γ by the Raman scattering of the corresponding NCs, but also a reference to completely understand the confinement effect of different modes in various nanomaterials.
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影响因子：
2.1
作者：
CAMPBELL, IH;FAUCHET, PM
通讯作者：
FAUCHET, PM
二维半导体中的缺陷激活光致发光：束缚激子、带电激子和自由激子之间的相互作用
影响因子：
4.6
作者：
Tongay, Sefaattin;Suh, Joonki;Ataca, Can;Fan, Wen;Luce, Alexander;Kang, Jeong Seuk;Liu, Jonathan;Ko, Changhyun;Raghunathanan, Rajamani;Zhou, Jian;Ogletree, Frank;Li, Jingbo;Grossman, Jeffrey C.;Wu, Junqiao
通讯作者：
Wu, Junqiao
影响因子：
8.6
作者：
Yao, Z;Kane, CL;Dekker, C
通讯作者：
Dekker, C
影响因子：
8.6
作者：
Mak, Kin Fai;Lee, Changgu;Heinz, Tony F.
通讯作者：
Heinz, Tony F.
DOI：
10.1103/physrevb.39.5907
发表时间：
1989-03
期刊：
Physical review. B, Condensed matter
影响因子：
--
作者：
Comas;Trallero-Giner;Riera
通讯作者：
Comas;Trallero-Giner;Riera