Electrons in Diamond

金刚石通常被认为是新一代电力电子的理想半导体材料。一个关键的应用将是电网的现代化，以整合能源、能源储存和不同用户的需求，如直流和交流电力系统。此外，从金刚石发射到水中的电子可以使各种应用的化学反应成为可能。这项研究将使用新的方法来改性金刚石及其表面，以实现这些应用。研究结果将支持金刚石功率晶体管、通信高频元件和电子发射到水中的发展，以进行其他材料不可能进行的局部化学反应。该项目将与ASU Sundial合作，该项目支持物理科学的保留和多样性。与日晷的活动包括与研究有关的讲习班，指导和发展一个面向社区成员和当地高中学生和教师的外联级科学会议。 这些活动的目的是通过提高这些学生的保留率和教育丰富机会，增加传统上代表性不足的学生进入科学事业的机会。技术说明金刚石是一种宽带隙半导体，具有出色的半导体特性，长期以来被认为有利于高功率和高频应用。由于具有特定的表面终止，金刚石具有负电子亲和力，可以将电子注入水中进行局部催化。 金刚石的高电子和空穴迁移率与所有其他宽带隙半导体相比是不寻常的。虽然用硼掺杂的p型已经被很好地表征了二十年，但用磷掺杂的n型最近在许多实验室中取得了进展，并且了解金刚石中的电子可以使新一代金刚石器件基于电子传输和电子从导带态发射到真空或水中。该提案的重点是电子注入和金刚石-电介质界面，以实现电子传输，限制和表面发射。该提案将解决在金刚石中实现电子的三个基本挑战：1）电子能否被传输到金刚石的导带中？金刚石的低或负电子亲和力意味着金刚石上接触金属的n型肖特基势垒将很大，并阻止电子注入。2)介电-金刚石界面能否形成，从而将电子限制在金刚石中？限制电子的电介质-半导体界面需要导带偏移，其中电介质导带最小值高于金刚石导带最小值。3)金刚石的表面终止能使电子持续有效地发射到真空或水中吗？虽然氢封端的金刚石具有负电子亲和力，但其表面在真空或包括水的氧化环境中不稳定。 从该项目中获得的理解将为金刚石作为电子半导体或局部催化剂的新应用奠定基础。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Nontechnical DescriptionDiamond is often considered as the ideal semiconductor material for a new generation of power electronics. A key application would be modernization of the electricity grid to integrate energy sources, energy storage and diverse users’ needs such as DC and AC power systems. Moreover, electrons emitted from diamond into water can enable chemical reactions for a variety of applications. The research will use new methods to modify diamond and its surface to enable these applications. The results will support the development of diamond power transistors, high frequency components for communications and electron emission into water for localized chemical reactions not possible with other materials. This project will collaborate with ASU Sundial, a program which supports retention and diversity in the physical sciences. The activities with Sundial include research related workshops, mentoring and the development of an outreach-level scientific conference, geared at community members and local high school students and teachers. The goal of these activities is to increase access to science careers to students who are traditionally under-represented, by improving retention and educational enrichment opportunities for these students.Technical Description Diamond is a wide band gap semiconductor with outstanding semiconductor properties that have long been recognized as beneficial for high power and high frequency applications. With specific surface termination, diamond has a negative electron affinity that can enable injection of electrons into water for localized catalysis. The high electron and hole mobilities of diamond are unusual compared to all other wide band gap semiconductors. While p-type doping with boron has been well characterized for two decades, n-type doping with phosphorus has recently advanced in a number of laboratories, and understanding Electrons in Diamond could enable a new generation of diamond devices based on electron transport and electron emission from conduction band states into vacuum or water. The focus of this proposal is on electron injection and diamond-dielectric interfaces to enable electron transport, confinement, and surface emission. This proposal will address three fundamental challenges to achieving Electrons in Diamond: 1) Can electrons be transported into the conduction band of diamond? The low or negative electron affinity of diamond means that the n-type Schottky barrier for contact metals on diamond will be large and prohibit electron injection. 2) Can a dielectric-diamond interface be formed that confines electrons in diamond? A dielectric-semiconductor interface to confine electrons requires a conduction band offset where the dielectric conduction band minimum is above the diamond conduction band minimum. 3) Can a surface termination of diamond enable continued efficient electron emission into vacuum or water? While hydrogen terminated diamond has a negative electron affinity, the surface is unstable in vacuum or oxidizing environments including water. The understanding gained from this program will set the stage for new applications of diamond as a semiconductor for electronics or localized catalysis.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.