Hypothesis on the conductivity mechanism in hydrogen terminated diamond films

An electrical model of the surface conductive layer in diamond induced by hydrogen plasma treatment is proposed. The model is discussed by analysing the characteristics of Schottky diodes and resistors built on the hydrogen terminated diamond. It is proposed that the hydrogen induced accepters in diamond are separated from the surface by a separation layer characterised by dielectric constant epsilon similar to 50 and thickness of about 30-50 nm. This layer allows the complete depletion of the hydrogen induced accepters by a 0.5-1 eV Schottky barrier, but prevents the tunneling through the barrier at forward bias. Also, this model allows charges on the surface of the proposed separation layer. The charging/discharging of surface states can explain the degradation of the device performance during testing. (C) 2000 Elsevier Science S.A. All rights reserved.