POST-PROCESSING OF DIAMOND AND DIAMOND FILMS - A REVIEW OF SOME HARWELL WORK

Diamond is an attractive material for electronic applications; however natural stones are often too small and inhomogeneous to be useful, so several processes have been developed to produce synthetic thin film diamond. Work on an ion beam process for epitaxial growth of thin film diamond is presented. Using C+ ion beams of up to 100 keV at temperatures from 350-1050-degrees-C, diamond thin films of up to 15-mu-m can be deposited at rates of up to 5-mu-m h-1. The ion beam method has also been modelled to take growth mechanisms, defect incorporation and film failures into account. The electrical behaviour of diamond has been studied by introducing electrically active dopants via ion implantation and annealing. Boron has been demonstrated to be a p-type dopant while lithium has been identified as an n-type dopant. A p-n junction has been produced by ion implanting a type 2B diamond stone with lithium. This junction displayed good I-V characteristics at room temperature and retained excellent properties at temperatures up to 350-degrees-C.