The variation of the electronic structure normal to 1D defects in quasi-freestanding MoS$_2$, grown by molecular beam epitaxy, is investigated through high resolution scanning tunneling spectroscopy at $5$K. Strong upwards bending of valence and conduction bands towards the line defects is found for the 4|4E mirror twin boundary and island edges, but not for the 4|4P mirror twin boundary. Quantized energy levels in the valence band are observed wherever upwards band bending takes place. Focusing on the common 4|4E mirror twin boundary, density functional theory calculations give an estimate of its charging, which agrees well with electrostatic modeling. We show that the line charge can also be assessed from the filling of the boundary-localized electronic band, whereby we provide a measurement of the theoretically predicted quantized polarization charge at MoS$_2$ mirror twin boundaries. These calculations elucidate the origin of band bending and charging at these 1D defects in MoS$_2$. The 4|4E mirror twin boundary not only impairs charge transport of electrons and holes due to band bending, but holes are additionally subject to a potential barrier, which is inferred from the independence of the quantized energy landscape on either side of the boundary.
Bending effects and optical properties of WSe2 nanoribbons of topological phase
1 T '相的WSe 2单层是一种大带隙量子自旋霍尔绝缘体，支持通过拓扑保护边缘态的无耗散电荷和自旋输运。在本工作中，我们通过第一性原理密度泛函计算和多体微扰GW和Bethe-Salpeter方程方法研究了1 T '相WSe 2的纳米取向形式。我们发现1 T 'WSe_2纳米晶体可以显示出拓扑边缘态，带宽约为4-6 nm。这些边缘带显示出奇数次穿过费米能级，其中一种自旋极化连接价带连续带和导带连续带。边缘带的拓扑特征即使在纳米尺度中的小和中等弯曲下也保持不变，而大的弯曲引起大的带分裂，导致边缘带的拓扑关闭。半导体化的1 T 'WSe 2纳米晶体在光吸收谱和激子态的弯曲方面表现出很大的可调谐性。最低能量激子从平坦纳米带中的光学暗变为弯曲纳米带中的光学亮。1 T 'WSe 2纳米带的这些性质表明了其在可控量子电子学和基于激子的量子信息过程中的潜在应用。
Simultaneous quantization of bulk conduction and valence states through adsorption of nonmagnetic impurities on Bi2Se3
将拓扑绝缘体Bi 2 Se 3的（111）表面暴露于一氧化碳导致在角分辨光电发射中观察到的特征的强烈移位。该行为非常类似于经常报道的表面的“老化”效应，并且可以得出结论，这种老化最有可能是由于其余气体分子的吸附。光谱变化也类似于最近报道的磁性吸附原子Fe的吸附。所有的光谱变化都可以用导带和价带态的同时限制来解释。这是唯一可能的，因为不寻常的体电子结构的Bi2Se3。价带量子化导致光谱特征类似于狄拉克点处的带隙开口的光谱特征。
