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）是最近发现的一个过程，我和我的学生一直在探索建造设备，设计用于感知存在于水环境中的带电生物分子，如细菌。这项受专利保护的应用是在我2015-2020年发现基金（DG）的支持下开发的，它利用了亚单层控制的GaAs/AlGaAs纳米异质结构在磷酸盐缓冲盐水悬浊液中的光溶解，以及光致发光信号对波段弯曲的敏感性。DIP工艺，a)不会引入外来的表面缺陷，通常在激光烧蚀，磁控溅射，等离子体蚀刻或一些传统的湿化学蚀刻技术中观察到，b)它可以通过关闭光生成载体的来源而突然终止，这与最先进的原子层蚀刻（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剪材料厚度和/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难以捉摸的自上而下的量子限制III-V纳米结构（例如，量子点或量子线）的制造，或任意形状的过渡金属二硫化物（TMDC）薄膜的单层，这需要一个强大的蚀刻程序尚未开发。因此，在我之前的DG项目成功的基础上，我建议探索DIP（照片- ale）用于III-V半导体纳米异质结构和TMDC薄膜的创新纳米结构。本项目的短期目标是建立a)导致蚀刻二元和三元III-V材料的化学计量表面形成的条件，b)启动TMDC薄膜的光- ale研究。该计划解决的战略重要问题之一，将涉及照片- ale暴露表面的原位钝化。这将利用完全在专用光流电池中进行的过程，并辅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三维量子约束和在TMDC薄膜中实现多层向单层转变的条件。中长期目标是使一些量子限制III-V器件和TMDC纳米器件原型的设计和制造技术更接近大量研究人员，从而有助于以潜在的高吸引力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.