Phosphorus carbides: theory and experiment

The recent finding that radio frequency plasma activation of CH4/PH3 gas mixtures can yield films with P : C ratios less than or equal to 3 has served to trigger further research into new 'phosphorus carbide' materials. Theoretical and experimental results relating to periodic and amorphous materials, respectively, are presented here: (i) The electronic structure and stability of different crystalline phosphorus carbide PxCy phases have been studied using first-principles density-functional theory. Calculations have been carried out for P4C3+8n (n = 0-4), PC, and PC3 and the most likely periodic structures examined in detail. Particular attention is paid to the composition PC3, for which there are several possibilities of similar energy. (ii) Recent experimental efforts have involved use of pulsed laser ablation 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 = 298-700 K), in vacuum, and analysed via laser Raman and X-ray photoelectron spectroscopy.