Mechanisms of surface conductivity in thin film diamond: Application to high performance devices

It has been known for some time that hydrogen within the bulk of diamond in creases the conductivity of the material. However, only recently did it bec ome apparent that the surface of thin film diamond can display p-type condu ctivity and that this too related to the presence of hydrogen. The origin o f this effect has been controversial. We have used a wide range of techniqu es to study hydrogenated polycrystalline CVD diamond films to solve this pr oblem. The generation of near surface carriers by hydrogen, which resides w ithin the top 20 nm of 'as-grown' CVD films, is the origin of the conductiv ity rather than surface band bending which had also been proposed. Up to 10 (19) holes cm(-3) can be measured and mobilities as high as 70 cm(2)/Vs rec orded. H-termination of the surface is important for the formation of high quality metal-diamond interfaces. (C) 1999 Elsevier Science Ltd. All rights reserved.