Diamond-based electron emission: Structure, Properties, and mechanisms

Abstract

Abstract Diamond has an ultrawideband gap with excellent physical properties, such as high critical electric field, excellent thermal conductivity, and high carrier mobility, etc. In particular, diamond with hydrogen-terminated (H-terminated) surface has a negative electron affinity (NEA) and can produce surface electrons from valence or trapped electrons easily via optical absorption, thermal heating energy, or carrier transport in a PN junction. The NEA of the H-terminated surface enables surface electrons to emit in high efficiency into the vacuum without encountering additional barriers and promotes further development and application of diamond-based emitting devices. This article reviews the electron emission properties of H-terminated diamond surfaces exhibiting NEA characteristics. The electron emission is induced by different physical mechanisms. The recent advancements in electron-emitting devices based on diamond are also summarized. Finally, the current challenges and future development opportunities are discussed to further develop the relevant applications of diamond-based electron emitting devices.