Field- and photo-emission properties of CVD-diamond with different microcrystalline structure

Electron emission properties of diamond films with different microstructures have been investigated by field- and photo-emission measurements, Both the crystalline quality of diamond and the amount of non-diamond carbon phases appear to largely affect the energy threshold for electron photoemission, as well as its intensity and spectral distribution, suggesting different types of transition occurring below and above the diamond band gap energy. A similar dependence on the amount of non-diamond carbon phases was also found for electric field threshold in field-emission measurements, where electric field enhancement effects related to the change of film morphology were also detected. The experimental results are discussed in terms of excitation of electrons out of defect states related to the diamond surface. (C) 2001 Elsevier Science B.V. All rights reserved.