论文标题
对Van-Waals异质结构中超快电荷转移的微观理解
Microscopic understanding of ultrafast charge transfer in van-der-Waals heterostructures
论文作者
论文摘要
Van-der-Waals异质结构显示出许多有趣的现象，包括在可见光谱范围内强烈的激光吸收后超快电荷分离。然而，尽管未来在光电子领域中应用的潜力巨大，但潜在的微观机制仍然存在争议。在这里，我们使用时间和角度分辨的光发射光谱与微观多粒子理论相结合，以揭示相关的显微镜电荷传递通道中的外延$ _2 $ _2 $/石墨烯异质结构。我们发现，材料中有效的超快电荷分离的时间尺度是通过在ws $ _2 $和石墨烯带交叉的布里渊区的那些点进行直接隧穿来确定的，而电荷分离瞬态状态的寿命是通过通过局部硫磺液通过固定的隧道来设置的。可以利用在本工作中揭示的固有和缺陷相关的电荷转移通道的微妙相互作用，以设计高效的光收集和检测设备。
Van-der-Waals heterostructures show many intriguing phenomena including ultrafast charge separation following strong excitonic absorption in the visible spectral range. However, despite the enormous potential for future applications in the field of optoelectronics, the underlying microscopic mechanism remains controversial. Here we use time- and angle-resolved photoemission spectroscopy combined with microscopic many-particle theory to reveal the relevant microscopic charge transfer channels in epitaxial WS$_2$/graphene heterostructures. We find that the timescale for efficient ultrafast charge separation in the material is determined by direct tunneling at those points in the Brillouin zone where WS$_2$ and graphene bands cross, while the lifetime of the charge separated transient state is set by defect-assisted tunneling through localized sulphur vacanices. The subtle interplay of intrinsic and defect-related charge transfer channels revealed in the present work can be exploited for the design of highly efficient light harvesting and detecting devices.
