Phosphorus carbide thin films: experiment and theory

The recent finding that radio frequency plasma activation of CH4/PH3 gas mixtures [7] could lead to films with P:C ratios less than or equal to3 (which also contain similar to10% hydrogen, distributed evenly throughout the bulk) has served to trigger further research into new 'amorphous phosphorus carbide' materials. New theoretical and experimental results relating to these materials are presented here. The electronic structure and stability of different crystalline phosphorus carbide PxCy phases have been studied using first-principles density-functional theory methods. Calculations have been carried out for both P4C3 and PC and a range of the more likely periodic structures examined. The lowest energy pseudocubic P4C3 and GaSe PC phases have been further investigated as templates to discover the stability and the electronic and structural properties of these phosphorus carbide materials. Recent experimental studies have involved use of pulsed laser ablation (PLA) methods to produce hydrogen-free phosphorus carbide thin films. Mechanically hard, electrically conducting diamond-like carbon films containing 0-similar to26 at. % P have been deposited on both Si and quartz substrates by 193 nm PLA of graphite/phosphorus targets (containing varying percentages of phosphorus), at a range of substrate temperatures (T-sub=25-400 degreesC), in vacuum, and analysed via laser Raman and X-ray photoelectron spectroscopy.