IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Thin Films Friday Sessions
       Session TF-FrM

Paper TF-FrM1
Synthesis and Characterization of Highly Conducting Nitrogen Doped Ultrananocrystalline Diamond Films

Friday, November 2, 2001, 8:20 am, Room 123

Session: Diamond and Related Materials
Presenter: J. Birrell, Argonne National Laboratory
Authors: J. Birrell, Argonne National Laboratory
O. Auciello, Argonne National Laboratory
S. Bhattacharyya, Argonne National Laboratory
J.A. Carlisle, Argonne National Laboratory
L.A. Curtiss, Argonne National Laboratory
A.N. Goyette, Argonne National Laboratory
D.M. Gruen, Argonne National Laboratory
J. Schlueter, Argonne National Laboratory
A.V. Sumant, Argonne National Laboratory
P. Zapol, Argonne National Laboratory
Correspondent: Click to Email
Diamond has many superior materials properties, yet its application in electronic devices is severely limited due to the difficulty of producing n-type thin films of sufficiently high conductivity. In this work ultrananocrystalline diamond (UNCD) films with up to 0.2% total nitrogen content were synthesized by a microwave plasma enhanced chemical vapor deposition (MPCVD) method using a CH@sub 4@ (1%)/Ar gas mixture with 1-20% nitrogen gas added. CN and C@sub 2@ radicals are identified in the plasma and both their relative and absolute concentrations change as N@sub 2@ gas is added. The morphology and transport properties of the films are both greatly affected by the presence of CN. High-resolution TEM data indicated that the grain size and GB width increase with the addition of more than 5% N@sub 2@ in the plasma. The electrical conductivity of the nitrogen-doped UNCD films increases by five orders of magnitude (up to 143 @ohm@@super -1@ cm@super -1@) with increasing nitrogen content. Conductivity and Hall measurements made as a function of film temperature down to 4.2 K indicate that these films have the highest n-type conductivity and carrier concentration demonstrated for phase-pure diamond thin films. Grain-boundary conduction is proposed to explain the remarkable transport properties of these films, in which nitrogen segregates to the grain-boundaries and promotes sp@super 2@ bonding and the introduction of more states into the fundamental gap, leading to enhanced electron transport. Work supported by the U.S. Department of Energy, BES-Materials Sciences, under Contract W-31-109-ENG-38.