Investigation of CaZrO _{3− <i>x</i>} S <i> _x </i> oxysulfide perovskite thin films grown by pulsed laser deposition

Abstract We aim to identify alternative perovskite candidates for optoelectronic and photovoltaic applications that would combine several key requirements, such as stability, low toxicity, scalability, abundance, and efficacy. Among the most promising candidates are chalcogenide and oxysulfide perovskites, such as CaZrS 3 or CaZrO 3− x S x . While several methods to grow such materials involve post-sulfurization of precursors, in this work, we investigate the direct growth of CaZrO 3− x S x films by pulsed laser deposition. Growth conditions were explored on various substrates, including LaAlO 3 (001) (LAO), SrTiO 3 (001) (STO), SrTiO 3 :Nb(001) (Nb:STO), YAlO 3 (001) (YAO), and Al 2 O 3 (1–102) (ALO), over a temperature range from 600 °C to 900 °C. The resulting films were systematically characterized in terms of their structural, optical and electrical properties, as well as their semiconducting energy levels. The most promising results were obtained on LAO substrates at a growth temperature of 800 °C, yielding improved crystallinity and a bandgap of 2.4 eV, the lowest among the investigated films. This film also exhibited a very high and promising surface photovoltage signal, reaching 900 mV at 0.2 sun. However, to further improve the material’s suitability for photovoltaic integration, particularly in single junction or tandem architectures, additional bandgap tuning via doping may be necessary to enhance electrical transport and broaden absorption.