Collaborative Research: FuSe: High-throughput Discovery of Phase Change Materials for Co-designed Electronic and Optical Computational Devices (PHACEO)

非技术描述存储和处理数据所需的能源需求正在以不可持续的速度增长。显然，我们需要新技术。相变材料在相变过程中可以极大地改变其电学、光学和物理性质，提供了一种很有前途的解决方案。它们的可调性使它们成为新兴应用(如高能效的内存计算)的潜在候选者。这一引信项目将探索一种新的相变材料，它将五种或五种以上元素以可比的数量组合在一起。材料科学领域已经被这种“高熵”材料的发现所吸引。例如，高熵陶瓷具有独特的热和机械性能，这是简单成分无法实现的。在这个项目中，研究人员将把计算材料发现和组合合成结合起来，实现高熵相变材料。最有希望的候选者将被全面描述，并集成到电子和光子计算设备中。该团队将建立一个强大的渠道来教育下一代劳动力。他们将提供轮流实习，这样学生就可以在不同的大学和交叉领域工作，并通过指导促进他们的成功。该团队还将在马里兰大学和HBCU霍华德大学之间建立合作伙伴关系，以促进研究指导和培训的直接交流。技术描述推动这个半导体未来项目的中心假设是，当元素随机占据一种类型的晶格位置并以高浓度而不是掺杂剂的形式存在时，高熵相变材料(PCM)可以形成热力学稳定的单相。这种结构由大的位形熵稳定，可用于发展低/零电阻漂移、大禁带宽度(1.5 eV)或大消光系数对比度(∆k~2-3)的光学忆阻器。拟议的研究包括四个主要专题，将以闭环方式进行。1)第一性原理计算材料发现来预测以前未探索过的熵稳定的相变材料。2)通过溅射硒、碲化物和硫化物的热蒸发进行组合合成，以便在一次运行中探索多种成分。3)电、光学、结构和组成材料的表征，以揭示材料的本征特性(介电常数、结构、振动模式、组成、电导率、电容等)以及决定器件性能的外部因素(孔洞形成、封顶、几何形状、衬底)。4)将相变材料集成到光子和电子设备中，以展示具有最佳性能的光和电记忆阻器和记忆电容器。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Non-technical DescriptionThe demand for energy needed to store and process data is growing at an unsustainable rate. New technologies are clearly needed. Phase change materials, which can dramatically change their electronic, optical, and physical properties during phase transitions, offer a promising solution. Their tunability makes them promising candidates for emerging applications such as energy efficient in-memory computing. This FuSe project will explore a new class of phase change materials that combine five or more elements in comparable amounts. The field of materials science has been captivated by the discovery of such “high entropy” materials. For example, high entropy ceramics have unique thermal and mechanical properties not possible with simpler compositions. In this project, investigators will combine computational materials discovery with combinatorial synthesis to realize high entropy phase change materials. The most promising candidates will be characterized comprehensively and integrated into electronic and photonic computational devices. The team will establish a robust pipeline to educate the next-generation workforce. They will offer rotational internships so that students can work at different universities and in cross-cutting fields and promote their success through mentoring. The team will also create a partnership between the University of Maryland and Howard University, an HBCU, to promote the direct exchange of research mentorship and training.Technical DescriptionThe central hypothesis driving this Future of Semiconductors project is that high-entropy phase change materials (PCMs) can form a thermodynamically stable single phase when elements randomly occupy one type of lattice site and are present in high concentrations rather than as dopants. This structure, stabilized by large configurational entropy, will enable development of PCMS with low/zero resistance drift and large bandgaps (1.5 eV) or extinction coefficient contrast (∆k~2-3) for optical memristors in the visible and infrared. The proposed research comprises four thrust topics to be conducted in a closed-loop fashion. 1) First-principles computation material discovery to predict previously unexplored entropy-stabilized PCMs. 2) Combinatorial synthesis via sputtering of selenides and tellurides and thermal evaporation of sulfides in order to explore multiple compositions in a single run. 3) Electrical, optical, structural, and compositional material characterization to reveal the intrinsic (permittivity, structure, vibrational modes, composition, conductivity, capacitance, etc.) and extrinsic (void formations, capping, geometry, substrates) factors dictating device performance. 4) Integration of PCMs into photonic and electronic devices to demonstrate optical and electrical memristors and memcapacitors with optimal performance.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.