Laser-Chemical Processing of Semiconductor Devices Based on Two-Dimensional Atomic Layer Materials

基于过渡金属二硫族化合物的二维原子层半导体由于其优异的光电性能而引起了人们的广泛关注。与硅相比，它们具有柔性电子产品的实质性优势，因为它们固有的柔性和它们的特性是高度可调的。然而，用传统方法制造它们非常困难，因为它们是原子薄且易碎的。该奖项旨在研究激光辅助化学加工，以制造具有超高灵敏度和非凡功能的稳定、高性能原子层半导体器件。它为过渡金属二硫族化合物基二维半导体器件的加工、功能化和图像化提供了一种新技术。二维半导体材料的化学成分被修饰和控制在纳米尺度上，通过激光照射从选定的气源中加入掺杂原子。这个过程在环境空气中是稳定的，并且能够精确调整材料的电子特性，这是制造高性能器件所必需的。这种耦合材料的合成、加工和表征方法为本科生和研究生（包括女性和少数民族）提供了重要的机会，以获得宝贵的研究经验和纳米科学与工程方面的培训。本项目的目的是利用激光驱动的化学处理在双光束处理系统中实现二维原子层半导体的局部功能化。该工艺包括以正常入射照射激光束以产生空位和另一同步紫外纳秒激光束平行照射目标样品以解离掺杂前驱体气体分子。通过这种方式，可以解耦和控制掺杂和合金化过程中涉及的机制。实现了近场光学处理以降低特征分辨率并生成高度定义的纳米级图案。探索可扩展性和集成到功能器件中，以演示大规模纳米制造。第一个贡献是在这些材料中稳定和空间可控地写入p和n掺杂域，然后通过激光诱导合金化故意调谐半导体带隙。第二个贡献是使用集成在激光CVD系统中的组装微透镜和纳米线元件对目标材料进行直接纳米化。通过制造具有尖锐纳米级PN结的晶体管和横向串联光电器件，验证了研究工作。最后，这个项目为发现这些奇异材料的全新和令人兴奋的物理学提供了一个强大的和可重复的平台。

Two-dimensional atomic layer semiconductors based on transition metal dichalcogenides have attracted intense interest due to their exceptional optoelectronic properties. Compared to silicon, they have substantial advantages for flexible electronics as they are inherently flexible and their properties are highly tunable. However, they have been very difficult to fabricate with conventional methods because they are atomically thin and fragile. This award investigates laser-assisted chemical processing to fabricate stable, high-performance atomic layer semiconductor devices with ultra-high sensitivity and extraordinary functionalities. It contributes a new technology for the processing, functionalization and patterning of transition metal dichalcogenide-based two-dimensional semiconductor devices. The chemical composition of the two-dimensional semiconductor materials are modified and controlled at the nanoscale by incorporating doping atoms from a selected gas source by means of laser irradiation. This process is stable in ambient air and enables precise tuning of the electronic properties of the material that is necessary for fabricating high performance devices. This coupled materials synthesis, processing and characterization methodology provides significant opportunities for undergraduate and graduate students, including women and minorities, to gain valuable research experiences and training in nanoscience and engineering.The objective of this project is to utilize laser driven chemical processing for localized functionalization of two-dimensional atomic layer semiconductors in a dual-beam processing system. The process involves a laser beam irradiated at normal incidence to generate vacancies and another synchronized ultraviolet nanosecond laser beam irradiated parallel to the target specimen for dissociation of dopant precursor gas molecules. In this manner, it is possible to decouple and control the mechanisms involved in the doping and alloying processes. Near-field optical processing is implemented to reduce feature resolution and generate highly defined nanoscale patterns. Scalability and integration into functional devices are explored to demonstrate large-scale nanomanufacturing. The first contribution entails stable and spatially controlled writing of p- and n-doped domains in these materials, followed by the deliberate tuning of the semiconductor band gap via laser induced alloying. The second contribution is the direct nanopatterning of the target materials using assembled microlens and nanowire elements integrated into the laser CVD system. The research work is validated by fabricating transistors having sharp nanoscale PN junctions and lateral tandem optoelectronic devices. Finally, this project offers a robust and repeatable platform for discovering entirely new and exciting physics of these exotic materials.