Theory of Electron Emission and Transport Properties of Diamond

Abstract

Electron field emission from diamond films was calculated using a model consisting of the projection of the energy-band surfaces in the <111>, <110> and <100> emission directions. It is found that the tunneling from bulk conduction and valance bands is negligible in p-type diamond, while emission from n-type doped diamond, surface states located near the conduction band edge, and hypothesized defect bands in the energy gap all have sufficient transmission probabilities to produce the low power-high current observed in experiments. To understand the mechanism for supplying electrons to these tunneling states, we analyze charge transport in diamond with internal fields. In particular, a Monte Carlo simulation was performed for electrons in the conduction band as a function of field and film thickness. The results predict hot electron behavior at lower fields with a transition to ballistic-like behavior for high fields (≥ 10 V/μm) and thin samples (≤0.1 μm). It is suggested that if a viable electron injection mechanism into the conduction band of a diamond-metal or diamond-semiconductor interface could be found for those faces of diamond exhibiting NEA, then a copious cold cathode electron emitter with field tunable energies is feasible.