Material World Network: Understanding and Exploiting Mixed-Mode Ultra-Fast Optical-Electrical Behavior in Nanoscale Phase Change Materials

本材料世界网络项目的目标是全面研究混合光电相变中相变材料的材料特性。Ge-Sb-Te合金中的存储器存储的基本原理是可逆的结晶到非晶相变，其与光学反射率和电阻率的显著变化相关联。 虽然已经独立地研究了光学和电学机制，但是没有对混合模式操作进行研究，即在电学探测的同时光学地切换材料，反之亦然。然而，这对于从光选通超快晶体管到非冯·诺依曼算术处理的许多潜在的改变游戏规则的应用来说是极其重要的。美国，英国和德国的PI之间的合作将专注于研究混合模式下的基本相位开关特性，通过动态光学探测电相变来阐明相变机制，并探索最适合于非传统未来算术处理器的材料。这项工作将涉及增长和表征的新组合物的相变纳米线，光脉冲感应开关，将被探测电，和详细的大小和成分依赖的研究混合模式操作nanowire.NON-TECHNICAL SUMMARYThe冯诺依曼模型的计算，这是目前使用的计算机架构，利用设计与单独的部门处理，逻辑和内存。虽然这种设计在今天的计算机上非常成功，但显然需要超越冯·诺依曼的模型，以跟上对具有前所未有的能力的更快计算机的不断增长的需求。通过光学激发将算术处理能力与电子存储器在公共平台上相结合是超越传统计算机架构的一种可能的解决方案，并且相变材料在这方面非常有前途。该材料世界网络项目计划首次研究相变材料的光电混合模式行为。虽然这些材料的显着性能使它们在存储器件中取得了商业上的成功，但控制它们在晶态和非晶态之间的相变的基本材料性能仍然是未知的。该项目将提供基本的和新颖的见解，这些材料的电学行为是如何受到光激发的影响，反之亦然。该研究旨在在三个参与国家的PI之间转移最好的业务。这项工作的结果将极大地影响非冯·诺依曼计算的发展，使用算术处理技术，可以彻底改变我们所知道的计算。研究和教育活动将通过本科生参与研究计划，将新的研究成果纳入教学模块，并培训来自三个国家当地学区的高中教师。此外，国际合作的机会将使学生有机会花时间在另一个实验室，并将提供一个独特的机会，追求跨越国界的前沿研究。该项目是由电子和光子材料计划和特别计划办公室，材料研究部的支持。

TECHNICAL SUMMARYThe objective of this Materials World Network project is to investigate comprehensively the material properties of phase change materials in mixed optical-electrical phase transitions. The underlying principle of memory storage in Ge-Sb-Te alloys is reversible crystalline to amorphous phase transitions that are associated with significant changes in optical reflectivity and electrical resistivity. Although the optical and electrical mechanisms have been independently investigated, there is no work done on the mixed-mode operation, i.e. switching the material optically while probing it electrically and vice-versa. This is however extremely important for a host of potentially game-changing applications ranging from optically gated ultra-fast transistors to non-von-Neumann arithmetic processing. This collaboration between PIs in US, UK and Germany will focus on investigating fundamental phase switching properties in mixed-mode, elucidating phase change mechanisms via dynamic optical probing of electrical phase transitions, and exploring the materials best suited for unconventional future arithmetic processors. The work will involve growth and characterization of new compositions of phase change nanowires, optical pulse induced switching which will be probed electrically, and detailed size- and composition-dependent studies of mixed mode operation in nanowires.NON-TECHNICAL SUMMARYThe von Neumann model of computing, which is currently used in computer architecture, utilizes designs with separate divisions for processing, logic and memory. Although this design has been highly successful for today's computers, there is clearly a need to go beyond von Neumann's model to keep up with the ever-increasing demand for faster computers with unprecedented capabilities. Combining arithmetic processing capabilities via optical excitation with electronic memory on a common platform is one possible solution to go beyond the conventional computer architecture and phase change materials are very promising in this regard. This Materials World Network project plans to study for the first time the optical-electrical mixed mode behaviour of phase change materials. Although the remarkable properties of these materials have made them commercially successful in memory devices, the fundamental material properties that govern their phase transitions between crystalline and amorphous states are still quite unknown. The project will provide fundamental and novel insights into how the electrical behaviour of these materials is influenced by optical excitation and vice versa. The research seeks to transfer best practises between PIs in three participating countries. The results of this work will greatly impact the development of non-von Neumann computing using arithmetic processing techniques that can revolutionize computing as we know it. Research and educational activities will be integrated by the involvement of undergraduates in the research program; incorporating new research results in the teaching module, and training high school teachers from the local school districts in three countries. In addition, international collaborative opportunities will give students opportunities to spend time in another laboratory and will provide a unique opportunity to pursue cutting edge research across national boundaries.This project is supported by the Electronic and Photonic Materials program and Office of Special Programs, Division of Materials Research.