Diamond grown by chemical vapour deposition (CVD) methods is thought to be
ideal for the fabrication of visible blind, fast deep UV photodetectors. Ho
wever, careful device design and selection of high-quality CVD thin film di
amond is, in itself, insufficient for the realisation of high performance d
evices. Post-growth device treatments are capable of transforming the optoe
lectronic properties of the material such that commercially interesting dev
ices result. In the present study we have shown that sequentially applied m
ethane-air treatments continue to modify both, the gain level and speed of
the device. Three such treatments give an optimal gain level, whilst more t
reatments than this lead to an improved turn-off speed. For the first time
we have demonstrated the successful operation of a CVD diamond photoconduct
ive device at at least 1 kHz at 193 nm, a frequency that is required for st
ate-of-the-art excimer laser applications at this wavelength. (C) 2000 Else
vier Science S.A. All rights reserved.