Digital photocorrosion of III-V semiconductors and transition metal dichalcogenides: fundamental and applied research of nanofabrication and molecular interactions at atomic level

数字光腐蚀（DIP）是一个最近发现的过程，我和我的学生一直在探索构建旨在检测含水环境中带电生物分子（如细菌）的设备。这项受专利保护的应用是在我的2015-2020发现资助（DG）的支持下开发的，它利用了GaAs/AlGaAs纳米异质结构在磷酸盐缓冲盐水悬浮液中的亚单层控制光溶解以及光致发光信号对能带弯曲的敏感性。DIP工艺，a）不引入通常在激光烧蚀、磁控溅射、等离子体蚀刻或在一些常规湿化学蚀刻技术中观察到的外来表面缺陷，和B）它可以通过切断光生载流子的源而突然终止，这与现有技术的原子层蚀刻（ALE）技术的自终止步骤相比。DIP工艺的这些参数对于在原子水平上修整材料厚度和/或提供高质量的三维纳米结构具有潜在的吸引力。这种发展的技术成果可能涉及量子限制的III-V族纳米结构的难以捉摸的自上而下的制造（例如，量子点或量子线），或过渡金属二硫属化物（TMDC）膜的任意形状单层，其需要尚待开发的稳健蚀刻程序。因此，在我以前的DG计划的成功的基础上，我建议探索DIP（光ALE）用于III-V族半导体纳米异质结构和TMDC薄膜的创新纳米结构。 该计划的短期目标是建立a）导致蚀刻的二元和三元III-V族材料的化学计量表面形成的条件，和B）启动TMDC膜的光ALE的研究。该计划解决的战略性重要问题之一，将涉及原位钝化的光ALE揭示的表面。这将利用完全在专用光流动池中进行的过程，并辅之以同时测量的光致发光（PL）或开路电位。利用光谱可分辨的PL，我们将研究在III-V量子阱微结构中实现3D量子限制的条件以及在TMDC薄膜中实现多层到单层的转变。中长期目标是使量子限制III-V族器件和TMDC纳米器件的一些原型的设计和制造技术更接近于大量研究人员，从而有助于以潜在的高度吸引力的成本提供这些材料的创新纳米制造技术的进步。

Digital photocorrosion (DIP) is a recently discovered process that my students and I have been exploring for building devices designed to sense electrically charged biomolecules, such as bacteria, present in aqueous environments. This patent-protected application, developed with the support of my 2015-2020 Discovery Grant (DG), takes advantage of both the sub-monolayer controlled photo-dissolution of GaAs/AlGaAs nanoheterostructures in phosphate buffered saline suspensions and the sensitivity of a photoluminescence signal to band bending. The DIP process, a) does not introduce extraneous surface defects, typically observed in laser ablation, magnetron sputtering, plasma etching, or in some conventional wet chemical etching techniques, and b) it could be abruptly terminated by switching off the source of photo-generated carriers, which compares to a self-terminated step of the state-of-the-art atomic layer etching (ALE) technique. These parameters of the DIP process are potentially attractive for trimming material thickness at the atomic level and/or delivering high-quality three-dimensional nanostructures. Technological outcomes of such a development could concern the elusive top-down fabrication of quantum confined III-V nanostructures (e.g., quantum dots or quantum wires), or arbitrary shape monolayers of transition-metal dichalcogenide (TMDC) films that require a robust etching procedure yet to be developed. Thus, building on the success of my previous DG program, I propose to explore DIP (photo-ALE) for an innovative nanostructuring of III-V semiconductor nanoheterostructures and TMDC films. The short-term objective of this program is to establish a) the conditions leading to formation of stoichiometric surfaces of etched binary and ternary III-V materials, and b) initiate the research of photo-ALE of TMDC films. One of the strategically important issues addressed with the program, will concern in situ passivation of the photo-ALE revealed surfaces. This will take advantage of the process carried out entirely in a dedicated photo-flow-cell, assisted with the simultaneously measured photoluminescence (PL) or open-circuit potential. With the spectrally resolvable PL, we will investigate the conditions for achieving 3D quantum confinement in III-V quantum well microstructures and a multilayer to single layer transition in TMDC films. The medium- to long-term objective is to bring the design and fabrication technology of some prototypes of quantum confined III-V devices and TMDC nanodevices closer to a large number of researchers and, thus, contribute to the advancement of an innovative nanofabrication technology of these materials offered at a potentially highly attractive cost.