Formation of shallow acceptor states in the surface region of thin film diamond

Considerable interest exists in fabrication of electronic devices from thin film polycrystalline diamond. To date, doping this material to achieve goo d free carrier concentrations and mobilities at room temperature has proved difficult. In this letter we report low temperature Hall effect measuremen ts made on diamond films subjected to a hydrogenation process, such that th e near surface region becomes p type without the addition of conventional d opant atoms. High carrier concentrations and mobilities can be achieved. Th e change in carrier concentration within the temperature range 10-300 K doe s not change as expected for most films, actually increasing as the tempera ture falls. This effect could be related to the confinement of carriers at the surface caused by the dipole provoked by adsorbed hydrogen on the diamo nd. However, polished films display more conventional behavior in that the carrier concentration falls with falling temperature. (C) 2001 American Ins titute of Physics.