Modification on the band structure and the related emission characteristics of defective diamond films doped with boron

Electron field emission properties of multilayer diamond films containing a n undoped diamond layer grown on top of boron-doped diamond layer are obser ved to be significantly superior to that of the single layer diamond films, boron-doped or undoped. The electron emission capacity (J(e)) of the multi layer diamonds increases as the thickness of the undoped layer reduces, wit h the turn-on field (E-0) and effective work function (phi(e)) essentially unchanged. This phenomenon is accounted for by the bending of the electroni c band structure, such that the electrons in the acceptor levels of the und erlying boron-doped layer can jump across the junction to the impurity band s in the top undoped layer, and then readily field emitted. The optimum ele ctron emission properties obtained are: J(e) = 4890 mu A/cm(2) (at 35 V/mu m), E-0 = 26 V/mu m and phi(e) = 0.28 eV. (C) 1999 Published by Elsevier Sc ience B.V. All rights reserved.