Electrons in Diamond

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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.