Eur. Phys. J. Special Topics 224, 1935-1943 (2015)
https://doi.org/10.1140/epjst/e2015-02511-y

Regular Article

Optimization of the molecular sieving properties of amorphous SiC_XN_Y:H hydrogen selective membranes prepared by PECVD

¹ Institut Européen des Membranes (UMR 5635 CNRS, ENSCM, UM), Université de Montpellier, cc047, Place Eugène Bataillon, 34095 Montpellier Cedex 5, France
² Laboratoire de Chimie Physique et Microbiologie pour l'Environnement (CNRS UMR 7564, Université de Lorraine), 405 rue de Vandoeuvre, 54601 Villers-lès-Nancy, France

^a e-mail: vincent.rouessac@univ-montp2.fr

Received: 11 December 2014
Revised: 21 May 2015
Published online: 30 July 2015

Abstract

In this work, low frequency PECVD a-SiC_xN_y:H thin films have been synthesized in the temperature range 25–300 ^∘C from hexamethyldisilazane precursor mixed with ammonia at various concentrations. A relevant correlation has been evidenced between the [N]/[C] atomic ratio in the gaseous phase and in the deposited thin films, allowing both prediction and control of the film microstructure. A simple method based on the analysis of the films FTIR spectra was proposed to determine the value of the [N]/[C] ratio and thus predict or adjust the gas transport properties of the membrane materials. Attractive ideal selectivities α*_He/N2 exceeding 90 with He permeance Π_He > 3.10⁻⁷ mol.s⁻¹.m⁻².Pa⁻¹ were measured at 150 ^∘C for the films prepared at 300 ^∘C with an optimum [N]/[C] atomic ratio in the range 0.1–1.5. These films behave as molecular sieve membranes with a thermally activated transport of helium.