Effect of plasma power on properties of a‐SiC:H films deposited by DC magnetron sputtering

Abstract

AbstractThe effect of plasma discharge power on the properties of a‐SiC:H thin films deposited by DC magnetron sputtering from the use of a liquid source based on hydrocarbon (triméthylphosphine: TMP, (P(CH3)3) are presented. The liquid source based of trimethylphosphine is introduced into the deposit chamber by using hydrogen as carrying gas. The samples were characterized by optical transmission, infrared absorption (FT‐IR) and electrical conductivity measurements. Optical transmission showed that the increase of the plasma discharge power induced a decrease in optical gap energy value accompanied by an increase of refractive index due to a reduction of Si‐H bonds and the carbon film content. Infra‐red absorption measurements clearly evidenced the appearance of additional bands relating to the constituent elements of the TMP (H, C, P). In the same way, a reduction in the phosphorus and carbon contents with the increase of the discharge power is observed. The electrical conductivity measurements have revealed a change of electrical properties of a‐Si:H(P) layers and the doping efficiency with the plasma power. They also clearly evidenced carbon incorporation in a‐Si:H matrix which limits the phosphorus doping effectiveness. The effect of the annealing temperature on the electric photoconductivity of material was also studied. We clearly evidenced that the a‐SiC:H(P) films are photoconductive with an improvement after a thermal annealing in the range of 130–250 °C correlated with an activation of the phosphorus atoms in the a‐Si:H matrix. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)