Ion-implantation in diamond and diamond films: doping, damage effects and their applications

Diamond is very special owing to its extremely strong, metastable, sp3 bonding. The tightness of the diamond crystal makes diffusion-doping of diamond or doping diamond during high-pressure high-temperature growth very difficult, if not impossible. Hence ion-implantation may be the method of choice for doping diamond, in a controlled way, thus opening up the possibility of its use as an electronic material. Ion-implantation in diamond, in CVD diamond or in diamond-like films is, however, complicated by the tendency of broken sp3 bonds to form the more stable graphite sp2 bonds which can give rise to non-doping related electrical conductivity. This paper reviews the current status of doping diamond and diamond films by ion-implantation. Special attention is given to ways of avoiding or utilizing ion-beam induced graphitization of diamond, and to attempts of achieving real reproducible n-type doping of diamond.