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

非技术描述：二维材料，如石墨烯和二硫化钼，已经引起了相当大的关注，因为它们可以提供一种在小型化的极限下制造电子器件的简便方法，即基于只有一层厚的惰性、稳定的原子层。在这个框架内，这个迫切的研究项目打算开发不同单层材料之间的横向连续转变的概念，其中材料的组成通过化学手段控制以快速转变，例如从二硫化钼到二硒化钼。最终目标是开发一种程序，通过这种程序，可以将明确定义的材料组成模式和随之而来的电子性质“编织”成单一的原子片，就像格子布中的图案一样。如果成功，这种方法将提供比传统方法更容易的器件结构制造。该项目是在一家拉美裔服务机构进行的，并直接使实验室中的多名拉美裔本科生和研究生受益。它与由首席研究员指导的本科生现场研究经验相结合。技术描述：该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卤化物单层薄膜中制备横向成分异质结的方法。它建立在首席研究员实验室的发现基础上，这些发现允许在任何成分的二硫化钼和二硒化钼之间制备合金。初步数据表明，可以制造出MEV/微米级的成分梯度。这项研究项目调查这些梯度是否可以足够锐利和控制，以便它们可以为单层器件建立量子井或其他功能元件。为此，研究人员通过硫-硒交换对薄膜生长过程中的硫化物注射和薄膜生长后的处理进行专门控制。表征主要通过光学光谱学进行，并辅之以电学测试，在那里取得了有希望的结果。如果该项目成功，所产生的结构将允许将目前作为现代光电子学基础的许多材料和器件概念转移到二维薄膜世界。

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.