SusChEM: Molecular Routes to New Classes of Polar and Non-Polar Alloy Semiconductors

技术说明：该项目研究了（III-V）-IV合金的制造和性能，基于最近发现的一种消除这些合金中相分离效应的合成方法。基本思想是从预先形成的分子单元构建合金晶体，该分子单元包含三个IV族原子和四面体几何中的单个III-V对。在容易获得的硅或锗衬底上使用化学气相沉积进行生长。该研究包括确定合金的原子级结构，系统研究其光学特性，调查潜在半导体应用的成分和掺杂控制，以及将该方法推广到包括大多数III，IV和V族材料。另一个目标是基于分子构建块的概念开发其他类别的材料。非技术描述：材料科学的现代研究主要集中在自然界中不可用的材料的设计和合成上。该项目所展示的晶体生长的分子方法代表了这一探索的新工具，可能会导致具有独特性能的材料。特别是，一些待研究的材料，包括Al、P、N和Si的合金，预计具有类似于硅晶体的晶格尺寸，并且可以形成Si基叠层太阳能电池的基础。单层硅太阳能电池主导了当前的光伏市场，但其效率仅限于约25%。在串联结构中，电池效率可以超过30%，具有巨大的社会影响。分子到固体方法的独特性也为多学科教育创造了机会。该项目包括开发新课程，使学生熟悉进行材料研究所需的化学和物理概念。此外，还准备建立一个化学前体数据库，供广大社区使用，以确保其他研究人员能够获得在该项目下开发的合成创新成果，该项目由材料研究司的电子和光子材料方案以及固态和材料化学方案共同资助。

Technical Description: The project investigates the fabrication and properties of (III-V)-IV alloys based on the recent discovery of a synthesis approach that eliminates phase segregation effects in these alloys. The essential idea is to build the alloy crystal from pre-formed molecular units containing three group-IV atoms and a single III-V pair in tetrahedral geometry. Growth is done using chemical vapor deposition on readily available silicon or germanium substrates. The research includes determination of the atomic level structure of the alloys, systematic study of their optical properties, investigation of compositional and doping control for potential semiconductor applications, and generalization of the approach to include most group III, IV, and V materials. An additional goal is to develop other classes of materials based on the concept of molecular building blocks.Non-technical Description: Modern research in materials science is strongly focused on the design and synthesis of materials not available in nature. The molecular approach to crystal growth exemplified by this project represents a new tool for this quest that may lead to materials with unique properties. In particular, some of the materials to be studied, including alloys of Al, P, N, and Si, are expected to have lattice dimensions similar to a silicon crystal and could form the basis for Si-based tandem solar cells. Single-layer silicon solar cells dominate the current photovoltaics market but their efficiency is limited to about 25%. The cell efficiency could exceed 30% in tandem structures, with large societal impact. The uniqueness of the molecules-to-solids approach also creates opportunities for multidisciplinary education. The project includes the development of new courses that allow students to become familiar with the chemistry and physics concepts needed to pursue materials research. Provisions are also being made to create a database of chemical precursors, to be made available to the community at large, which insures that other researchers have access to the synthetic innovations developed under this project.This project is funded jointly by the Electronic and Photonic Materials (EPM) and Solid State and Materials Chemistry (SSMC) Programs in the Division of Materials Research.