Interface engineering for covalently bonded disordered thin films: boron nitride and diamond-like carbon

Covalently bonded disordered thin films, boron nitride (BN) and diamond-lik e carbon (DLC), have been synthesized by two energetic deposition processes , ion beam-assisted deposition (IBAD) and filtered are deposition (FAD), re spectively. Interface engineering has been conducted for these two films to solve the adhesion and held electron emission problems. For the IBAD BN fi lm, a TiN buffer layer has been built between the BN film and silicon subst rate. Delimitation of BN films from substrates, which happens in convention al BN single layer thin films, does not occur with this approach. Structura l investigation reveals that the BN layer is cubic phase dominated the smal l amount of hexagonal phase in the layer located at the interface region cl ose to the underlying TiN layer. Evidence of TiB2 formation at the interfac e between BN and TiN has been demonstrated. For the FAD DLC thin film, whic h is a very attractive cathode material for field electron emission, an int ermediate layer of metal Ti has been added between the DLC film and silicon substrate. Then the held emission characteristics of the DLC/Ti films have been studied using a diode structure in comparison with the DLC films with out the Ti interfacial layer. It is found that the Ti intermediate layer pl ays a significant role in improving field emission properties of the FAD DL C thin films. Exceptional field emission performance has been achieved by p ost-deposition annealing of the DLC thin films with a TiN transition layer. Formation of TIC at the interface, lowering the Schottley barrier for elec tron transportation from substrate to the DLC thin film, is believed to con tribute to the improved field emission. (C) 2000 Elsevier Science B.V. All rights reserved.