OP: Interlayer Excitons in Double Layer Black Phosphorus

非技术描述：当半导体吸收光时，电子可以被提升到更高的能级，并留下一个空穴。带负电的电子和带正电的空穴之间的吸引力会使两个粒子粘在一起。这种结合的电子-空穴对称为激子。在一类原子级薄的新型半导体中，激子非常稳定，即使在室温下也是如此。研究小组的目标是通过实验和理论来了解黑磷中激子的行为，并找出是否有可能在这类材料中使用激子来构建潜在的变换器光电器件。特别是，双层黑磷（由绝缘间隔层隔开的两层原子薄层）为激子的探索提供了令人信服的特性组合，包括更长的激子寿命和组成激子的正负电荷的垂直方向。这两种性质，结合黑磷相对较高的导电性，将促进该材料中激子的基础研究和器件应用。这项研究活动为广泛的高中生、本科生和研究生群体提供指导和培训。外展活动的重点是鼓励阿肯色大学招收代表性不足的群体。技术描述：没有3D体的筛选，2D材料产生强库仑相互作用，因此在高温下宿主激子。本项目旨在描述和了解原始、封装、少层黑磷中激子的基本性质。如果有足够的载流子迁移率和激子寿命，就有可能制造出将激子从电路的一部分传输到另一部分的激子装置。激子的这种运动可以用来编码和传输信息，也可以用来在纳米级结构中调制光信号。特别是，双层黑磷（由介电间隔层隔开的两个原子薄层）为激子的探索提供了令人信服的特性组合，包括增强的寿命，相对较高的各向异性迁移率，以及通过非均匀电场促进激子运动控制的垂直排列的偶极子。研究小组测量并分析了激子能量、线宽、位置和寿命作为黑磷厚度、温度和电荷密度（包括电子和空穴）的函数，以提供原始黑磷的基本材料特性。这些信息为有效的理论模型提供了输入，该模型指导了激子由门电压控制的激子器件的创建和理解。

Nontechnical description: When a semiconductor absorbs light, an electron can be promoted to a higher energy level and leave behind a hole. The attraction between the negatively charged electron and the positively charged hole can cause the two particles to stick together. This bound electron-hole pair is called an exciton. In a new class of atomically thin semiconductors, excitons are extraordinarily stable, even at room temperature. The research team aims to understand, using both experiment and theory, the behavior of excitons in black phosphorus, and to find out whether it will be possible to construct potentially transformative optoelectronic devices using excitons in this class of materials. In particular, double layer black phosphorus (two atomically thin layers separated by an insulating spacer) provides a compelling combination of properties for the exploration of excitons, including longer exciton lifetimes and vertical orientation of the positive and negative charges making up the exciton. Both of these properties, combined with the relatively high electrical conductivity of black phosphorus, will promote both the fundamental study and device applications of excitons in this material. This research activity provides mentoring and training of a widely inclusive group of high school, undergraduate, and graduate students. Outreach activities focus on encouraging the enrollment of underrepresented groups at the University of Arkansas.Technical description: Absent screening by a 3D bulk, 2D materials generate strong Coulomb interactions and therefore host excitons at high temperatures. This project aims to characterize and understand the basic properties of excitons in pristine, encapsulated, few-layer black phosphorus. Given sufficient carrier mobility and exciton lifetimes, it is possible to create excitonic devices that transport excitons from one part of a circuit to another. This movement of excitons could be used to encode and transmit information, or it could be used to modulate optical signals in a nanoscale structure. In particular, double layer black phosphorus (two atomically thin layers separated by a dielectric spacer) provides a compelling combination of properties for the exploration of excitons, including enhanced lifetimes, relatively high and anisotropic mobility, and vertically-aligned dipoles that promote control of exciton motion by non-uniform electric fields. The research team measures and analyzes exciton energies, linewidths, positions, and lifetimes as a function of black phosphorus thickness, temperature, and charge density (both electrons and holes) to provide baseline material properties of pristine black phosphorus. This information provides input to effective theoretical models, which guides the creation and understanding of excitonic devices in which excitons are controlled by gates voltages.