EAGER: Lateral Heterojunctions: Fabrication & Characteristics of a Novel Concept in 2D Materials Electronics

非技术描述：石墨烯和二硫化钼等二维材料引起了相当大的关注，因为它们可以提供一种简单的方法来制造电子设备，达到微型化的极限，即基于惰性的、稳定的原子片，只有一层厚。在这个框架内，这个EAGER研究项目打算发展不同单层材料之间横向连续过渡的概念，其中材料的成分通过化学手段控制迅速过渡，例如从二硫化钼到二硒化钼。最终目标是开发一种程序，通过该程序，材料组成的明确模式和随之而来的电子特性可以“编织”成单个原子片，就像格子布上的图案一样。如果成功，这种方法将提供比传统方法更容易制造的器件结构。这个项目是在一个西班牙裔服务机构进行的，直接使实验室里的许多西班牙裔本科生和研究生受益。它与由主要研究者指导的本科生研究经验网站协同作用。技术描述：本项目旨在开发利用改进的化学气相沉积方法在过渡金属二硫化物单层薄膜中制备横向组成异质结的方法。它建立在主要研究者实验室的发现之上，这些发现允许以任何成分制备二硫化钼和二硒化钼之间的合金。初步数据表明，该方法可以制备meV/微米尺度上的成分梯度。这个研究项目调查这些梯度是否可以足够尖锐和可控，以便它们可以为单层器件建立量子阱或其他功能元件。为此，研究人员在薄膜生长过程中专门控制加硫量，并通过硫硒交换对薄膜进行生长后处理。表征主要通过光谱学进行，并辅以电气测试，从而获得有希望的结果。如果该项目取得成功，所得到的结构将允许将当前GaAs/GaAlAs异质结技术的许多材料和器件概念转移到二维薄膜世界，这是许多现代光电子学的基础。

Non-technical Description: Two-dimensional materials such as graphene and molybdenum disulfide have attracted considerable attention because they may offer a facile way of fabricating electronic devices at the ultimate limit of miniaturization, i.e., based on an inert, stable atomic sheet that is only a single layer thick. Within this framework, this EAGER research project intends to develop the concept of lateral continuous transitions between different single-layer materials, in which the composition of the material is controlled by chemical means to transition rapidly, e.g., from molybdenum disulfide to molybdenum diselenide. The ultimate goal is to develop a procedure by which well-defined patterns of material composition and ensuing electronic properties can be "woven" into a single atomic sheet like a pattern in a plaid cloth. If successful, this approach will provide for significantly more facile fabrication of device structures than the conventional approach. This project is conducted at a Hispanic Serving institution and directly benefits multiple Hispanic undergraduate and graduate students in the lab. It synergizes with a Research Experience for Undergraduate students site directed by the principle investigator.Technical Description: This project intends the development of methods for the preparation of lateral compositional heterojunctions in transition metal dichalcogenide single-layer films utilizing a modified chemical vapor deposition approach. It builds on findings in the principle investigator's lab that permit the preparation of alloys between molybdenum disulfide and molybdenum diselenide at any composition. Preliminary data show that compositional gradients on the meV/micrometer scale can be fabricated. This research project investigates whether these gradients can be made sufficiently sharp and controlled so that they can set up quantum wells or other functional elements for single-layer devices. To this end, researchers apply both dedicated control of the chalcogen injection during the film growth and post-growth processing of films by sulfur-selenium exchange. Characterization proceeds primarily by optical spectroscopy augmented by electrical testing where promising results are achieved. If the project has success, the resultant structures will permit transfer of many materials and device concepts of current GaAs/GaAlAs heterojunction technology, which is the base of much of modern optoelectronics, to the world of two-dimensional films.