Electrons in Diamond

Project: Research project

Project Details


Overview: Diamond is a wide band gap semiconductor with outstanding semiconductor properties that have long been recognized for high power and high frequency applications. Diamond has the highest known thermal conductivity, which enables high power operation. The high electron and hole mobilities of diamond are unusual compared to all other wide band gap semiconductors, and support both high power and high frequency applications.

Intellectual Merit: 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. Examples would include efficient bipolar transistors, high frequency diodes for receiver protect circuits or microwave switching, inversion mode MOSFETs, vacuum electron emission diodes for power switches or high frequency amplifiers, and sources of electrons for local catalytic processes.

The focus of this proposal is on electron injection and diamond-dielectric interfaces to enable electron transport, confinement, and surface emission. Diamond is known to have a negative electron affinity, which impacts i) the ability to form electron injection contacts (i.e. electrons in diamond), ii) the selection of a dielectric layer to form a dielectric-diamond interface that confines electrons, and iii) the design of an ultra thin dielectric passivation layer to enable electron emission from conduction band states into vacuum (or water). 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.

This experimental project will employ state-of-the-art doped diamond layers and in situ interface studies using wide band gap oxide, nitride and fluoride dielectric layers to address the challenges.

Broader Impacts: The research presented here addresses one of the greatest challenges in advancing diamond electronics. The research would enable diamond bipolar transistors, high frequency diodes for microwave switching, inversion mode field effect transistors, vacuum electron emission diodes for power switches or and sources of electrons for local catalytic processes not possible with other materials. In addition, the project provides laboratory training for students to advance the science and technology that will drive this field. This project will also collaborate with ASU Sundial, a program which supports retention and diversity in the physical sciences. The activities developed with Sundial will 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, with an expected attendance of over 200. The goals 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.
Effective start/end date7/1/206/30/23


  • National Science Foundation (NSF): $563,616.00


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