Ion beam assisted deposition of tantalum carbide thin films for cold cathode

摘要

We deposited tantalum carbide thin films by ion beam assisted deposition and evaluated their properties. Tantalum atoms were evaporated from &beam evaporator and the carbon atoms were supplied as an ion beam produced by microwave plasma with methane gas. The microwave ion source was originally developed by the present authors. Prior to the deposition, we performed the mass analysis of the hydrocarbon ions, and found that the ion beam consisted of monomer to trimer. Several samples were deposited at room temperature with different hydrocarbon ion current. We measured carbon composition, crystallinity, electrical resistivity and work function. As a result, some of the films exhibited x-ray diffraction peaks of tantalum carbide, even though the deposition was made at room temperature. We also found that the work function increased with an increase in the carbon composition.