Homoepitaxial growth on fine columns of single crystal diamond for a field emitter

We have fabricated a pyramidal emitter array on single crystal diamond using an etching technique and a homoepitaxial growth technique. We carried out homoepitaxial growth on fine columns of a single crystal diamond in an NIRIM-type microwave-plasma-assisted chemical vapor deposition reactor in the undoped condition. It was found that temperature and methane concentration had a great influence on the oriented growth. We have found that there is a substantial tendency for a lower methane concentration to result in < 111 >-oriented growth and for a higher methane concentration to give < 100 >-oriented growth for a polycrystalline diamond film on Si. By controlling the growth conditions, we have obtained various shapes of diamond particle (cubic, cuboctahedral, octahedral) and have also fabricated a pyramidal sharp tip on single crystal diamond (100) and (110) surfaces. For a (100) substrate, we found that a fine pyramid tip was surrounded by not only four {111} planes but also four slightly slopes faces at the base. We surmise that the crystalline face agreed with the slightly doped plane and grew selectively because it has the highest lateral growth rate among the other oriented crystalline faces. For a (110) substrate, a fine pyramidal tip was surrounded by two {100} planes and two {111} planes and the top of the tip had a ridge betu een two {111} planes because of the less than optimum conditions. The field emission from the (100) and (110) substrates was also measured. The emission current of the (110) substrate was comparatively large. (C) 2000 Elsevier Science S.A. All rights reserved.