Enhancing the electrical conduction in amorphous carbon and prospects for device applications

The problems and possible solutions associated with producing practical electronic devices based upon amorphous carbon (a-C) thin films are discussed. The clustering of the carbon sp(2) phase is shown to be a critical aspect in understanding the current device limitations. In order to exploit the sp(2) clustering we show that the use of ion beams to deposit energy into the microstructure in a controlled manner, as opposed to conventional thermal anneal treatments, results in a delocalised electron wavefunction and an enhancement of conductivity. A barrier controlled device is demonstrated by carefully choosing the ion energy and dose. One of the consequences of ion implantation is that film can now be considered as consisting of conductive sp(2) C clusters within an insulating sp(3) C matrix. We show that the presence of this dielectric inhomogeneity between the conductive sp(2) regions and the sp' matrix plays an important role in understanding the field emission behaviour from a-C based materials. (C) 2003 Elsevier Science B.V. All rights reserved.