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引力可以使两个粒子粘在一起。这种束缚电子-空穴对称为激子。在一类新的原子薄半导体中，激子非常稳定，即使在室温下也是如此。该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，并找出是否有可能利用这类材料中的激子来构建潜在的变革性光电子器件。特别是，双层黑磷(由绝缘隔离层隔开的两个原子薄层)为探索激子提供了令人信服的性质组合，包括更长的激子寿命和组成激子的正负电荷的垂直方向。这两个性质与黑磷相对较高的导电性相结合，将促进激子在这种材料中的基础研究和器件应用。这项研究活动为广泛包容的高中生、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在阿肯色大学招收代表不足的群体。技术描述：在没有3D批量筛选的情况下，2D材料会产生强烈的库仑相互作用，从而在高温下产生激子。该项目旨在表征和了解原始的、封装的、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，就有可能创造出将激子从电路的一个部分传输到另一个部分的激子装置。激子的这种运动可以用来编码和传输信息，也可以用来调制纳米结构中的光信号。特别是，双层黑磷(由介电隔离物隔开的两个原子薄层)提供了探索激子的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垂直排列的偶极子，这些偶极子促进了不均匀电场对激子运动的控制。研究小组测量和分析激子能量、线宽、位置和寿命作为黑磷厚度、温度和电荷密度(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，这些模型指导了激子由栅极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.