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

技术摘要本材料世界网络项目的目的是全面研究相变材料在混合光电相变中的材料特性。Ge-Sb-Te合金中记忆存储的基本原理是可逆的晶体到非晶态相变，这种相变与光学反射率和电阻率的显著变化有关。虽然光学和电学机制已经被独立研究，但混合模式操作方面还没有工作，即在进行光学切换的同时进行电探测，反之亦然。然而，这对于从光门控超高速晶体管到非冯-诺伊曼算法处理等一系列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开关特性，通过电相变的动态光学探测阐明相变机制，并探索最适合非常规未来算术处理器的材料。这项工作将涉及到相变纳米线的新成分的生长和表征，将被电探测的光脉冲诱导开关，以及纳米线中混合模式操作的详细的尺寸和成分依赖研究。非技术总结冯·诺伊曼计算模型，目前用于计算机体系结构，利用单独划分处理、逻辑和存储器的设计。尽管这种设计在今天的计算机上非常成功，但显然需要超越冯·诺伊曼的模型，以跟上对具有前所未有的能力的更快的计算机不断增长的需求。在一个共同的平台上，结合通过光激发和电子存储器的算术处理能力是超越传统计算机体系结构的一种可能的解决方案，相变材料在这方面是非常有前途的。这个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。尽管这些材料的显著特性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相变的基本材料特性仍然是相当未知的。该项目将为这些材料的电学行为如何受到光激发的影响提供基础和新颖的见解，反之亦然。这项研究寻求在三个参与国的私人投资机构之间转移最佳做法。这项工作的结果将极大地影响使用算术处理技术的非冯·诺伊曼计算的发展，这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相结合；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，追求尖端的研究跨越国界。本项目由电子与光子材料项目和材料研究部特殊项目办公室支持。

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.