Carrier generation within the surface region of hydrogenated thin film polycrystalline diamond

Low temperature Hall effect measurements made on diamond films subjected to a hydrogenation process, such that the near surface region becomes p-type without the addition of conventional dopant atoms, are reported. The carrie r concentration within the temperature range 10-300 K does not change as ex pected for most films, actually increasing as the temperature falls. Howeve r, polished films display more conventional behaviour in that the carrier c oncentration falls with falling temperature. A model involving carrier tran sport within both valance and impurity bands can be considered to explain t hese observations, leading to the suggestion that the hydrogenation process is capable of creating acceptor states with an activation energy within th e range of 10-40 meV. (C) 2001 Elsevier Science B.V. All rights reserved.