Aerosol-assisted chemical vapor deposited Cu2S structured films with photo activated NO2 sensing properties

Abstract

Tetraethyl diphosphine disulfide copper complex [Cu(Et 4 P 2 S 2 )Cl] 2 is synthetized and used as a single source precursor for the deposition of copper sulfide (Cu 2 S) thin films by the aerosol-assisted chemical vapor deposition (AACVD) technique. Results reveal the AACVD formation of particle- and flake-like film morphologies at deposition temperatures of 400 °C and 450 °C, respectively, in agreement with the decomposition profiles of [Cu(Et 4 P 2 S 2 )Cl] 2 complex. As-deposited films present a tetragonal Cu 2 S phase that after annealing at 250 °C shows a transition to a cubic Cu 2 S phase. Further increase of the annealing temperature to 350 °C causes a transformation of Cu 2 S into CuO. The sensing properties of the as-deposited and annealed (250 °C) films to NO 2 using photo activation shows better performance for the annealed films in term of repeatability and response intensity. The flake-based sensors, in particular, exhibited a higher response and higher sensitivity to NO 2 , with a faster response time compared to the particle-based sensors.