Understanding pulsed laser deposition process of copper halides via plasma diagnostics techniques

Abstract

Due to the raised interest in copper halides for optoelectronic applications, a wide range of plasma diagnostic tools based on Langmuir probe (LP) and optical emission spectroscopy (OES) were implemented to investigate the pulsed laser deposition (PLD) process of selected copper halides. This represents the first report of complete diagnostics of copper halide plasma generated by laser ablation. High plasma potential and electron temperature were observed by a time-resolved LP analysis, which affected the kinetic energy of the ejected ions during expansion. The effect of argon gas addition on the copper halide plasma dynamics was investigated. Angle-resolved measurements revealed a narrow cone plasma expansion with a dual peak charge particle distribution, which was affected only above 2 Pa of Ar atmosphere. Plasma potential, charge density, and electron excitation temperature were increasing with Ar pressure, while electron temperature and expansion velocities were decreasing. Using a semi-empirical model, the estimation of an ion acceleration field, neutral temperature, and densities were computed. Space- and time-resolved OES confirmed the plume splitting indicated by LP measurements and provided insight into the composition of the two-plasma structure. All the plasma parameters were investigated in conditions similar to those used for thin film growth, and the results were discussed with respect to the PLD technology.