INFLUENCE OF FILM DEPOSITION PARAMETERS ON THE FIELD-EMISSION PROPERTIES OF DIAMOND-LIKE CARBON-FILMS

Considerable interest exists in the use of carbon-based materials as t he active phase in field emission devices for flat panel displays and vacuum electronics, in view of the observation that efficient field em ission can take place in fields as low as 0.2 V mu m(-1). Diamond has often been the focus of study since the material is generally very wel l characterised. Diamond-like carbon (DLC) is, however, possibly a mor e interesting candidate for practical devices since it is cheaply prod uced over large areas. Variation in the nature of DLC films is much gr eater than is the case for diamond, and understanding how the field em ission characteristics relate to the film properties is a key issue. I n this work, we therefore investigate field emission from DLC films an d study the relationship between emission properties and film depositi on parameters. DLC films were deposited on p-type and n-type Si substr ates from CH4/Ar and CH4/N-2 plasmas created by a pulsed mid-frequency symmetrical discharge operated at a few Torr. Film thicknesses in the range of 0.05-1.5 mu m were explored with optical band gaps ranging f rom 0.8 to 2.4 eV. The field emission properties of such films were fo und to vary markedly with the film characteristics, with turn-on field s as low as 1 V mu m(-1) being observed in some instances. The mechani sms that influence the field emission characteristics of the films are discussed. (C) 1998 Published by Elsevier Science S.A.