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双轴拉伸应变对二硫化钼单层能带结构的影响
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作者 郭菲 陶苏云 《化工设计通讯》 CAS 2021年第10期38-39,共2页
研究了室温下双轴拉伸应变对2H型二硫化钼单层电子能带结构和声子谱的影响。研究结果表明,二硫化钼单层的电子能隙随应变强度的增加而线性递减,而声子谱与应变的依赖关系则较弱,意味着在所考虑的应变强度范围内,材料结构并没有被破坏,... 研究了室温下双轴拉伸应变对2H型二硫化钼单层电子能带结构和声子谱的影响。研究结果表明,二硫化钼单层的电子能隙随应变强度的增加而线性递减,而声子谱与应变的依赖关系则较弱,意味着在所考虑的应变强度范围内,材料结构并没有被破坏,为进一步研究室温下双轴拉伸应变对受电子-声子散射影响的二硫化钼单层的载流子迁移率的影响奠定了良好的基础。结果完全是基于第一性原理计算得到,没有采用任何经验参数,因此计算结果对实验具有可靠的理论指导依据。 展开更多
关键词 双轴拉伸应变 二硫化钼 单层电子能带结构 声子谱
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Strain-induced direct-indirect bandgap transition and phonon modulation in monolayer WS2 被引量:26
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作者 Yanlong Wang Chunxiao Cong +7 位作者 Weihuang Yang Jingzhi Shang Namphung Peimyoo Yu Chen Junyong Kang Jianpu Wang Wei Huang Ting Yu 《Nano Research》 SCIE EI CAS CSCD 2015年第8期2562-2572,共11页
In situ strain photoluminescence (PL) and Raman spectroscopy have been employed to exploit the evolutions of the electronic band structure and lattice vibrational responses of chemical vapor deposition (CVD)-grown... In situ strain photoluminescence (PL) and Raman spectroscopy have been employed to exploit the evolutions of the electronic band structure and lattice vibrational responses of chemical vapor deposition (CVD)-grown monolayer tungsten disulphide (WS2) under uniaxial tensile strain. Observable broadening and appearance of an extra small feature at the longer-wavelength side shoulder of the PL peak occur under 2.5% strain, which could indicate the direct-indirect bandgap transition and is further confirmed by our density-functional-theory calculations. As the strain increases further, the spectral weight of the indirect transition gradually increases. Over the entire strain range, with the increase of the strain, the light emissions corresponding to each optical transition, such as the direct bandgap transition (K-K) and indirect bandgap transition (F-K, ≥2.5%), exhibit a monotonous linear redshift. In addition, the binding energy of the indirect transition is found to be larger than that of the direct transition, and the slight lowering of the trion dissociation energy with increasing strain is observed. The strain was used to modulate not only the electronic band structure but also the lattice vibrations. The softening and splitting of the in-plane E' mode is observed under uniaxial tensile strain, and polarization-dependent Raman spectroscopy confirms the observed zigzag-oriented edge of WS2 grown by CVD in previous studies. These findings enrich our understanding of the strained states of monolayer transition-metal dichalcogenide (TMD) materials and lay a foundation for developing applications exploiting their strain-dependent optical properties, including the strain detection and light-emission modulation of such emerging two-dimensional TMDs. 展开更多
关键词 monolayer WS2 strain light-emission tuning indirect transition TRION crystallographic orientation
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Growth and low-energy electron microscopy characteri- zation of monolayer hexagonal boron nitride on epitaxial cobalt 被引量:7
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作者 Carlo M. Orofeo Satoru Suzuki Hiroyuki Kageshima Hiroki Hibino 《Nano Research》 SCIE EI CAS CSCD 2013年第5期335-347,共13页
Low-energy electron microscopy (LEEM) has been used to study the structure, initial growth orientation, growth progression, and the number of layers of atomically thin hexagonal boron nitride (h-BN) films. The h-B... Low-energy electron microscopy (LEEM) has been used to study the structure, initial growth orientation, growth progression, and the number of layers of atomically thin hexagonal boron nitride (h-BN) films. The h-BN films are grown on heteroepitaxial Co using chemical vapor deposition (CVD) at low pressure. Our findings from LEEM studies include the growth of monolayer film having two, oppositely oriented, triangular BN domains commensurate with the Co lattice. The growth of h-BN appears to be self-limiting at a monolayer, with thicker domains only appearing in patches, presumably initiated between domain boundaries. Reflectivity measurements of the thicker h-BN films show oscillations resulting from the resonant electron transmission through quantized electronic states of the h-BN films, with the number of minima scaling up with the number of h-BN layers. First principles density functional theory (DFT) calculations show that the positions of oscillations are related to the electronic band structure of h-BN. 展开更多
关键词 chemical vapor deposition COBALT domain boundaries hexagonal boron nitride low-energy electronmicroscopy (LEEM)
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