Highly sensitive and wide range hydrogen sensor based on thin films of AgInO2 by pulsed laser deposition

Abstract

There has been mounting effort in the research on delafossite compounds due to their fascinating layered structure, chemical or optoelectronic properties for a wide range of industrial applications. However, thin film synthesis is known to be extremely challenging owing to their low symmetry rhombohedral structures, which limit the selection of substrates for thin film growth. In this study, AgInO2 is deposited on glass substrate by pulsed laser deposition at 0.7 mbar in-situ oxygen pressure, far higher than the usual range of 0.05–0.17 mbar for growth of multicomponent oxides for the first time. Stabilization of Ag+ ion as Ag2O is the crucial step which requires 0.7 mbar oxygen pressure for Ag particles free AgInO2. The deposited thin films show n-type behaviour with a carrier concentration of 1.1 × 1016 cm−3 at room temperature. Gas sensing studies revealed that thin films were highly selective to hydrogen with a significant reduction in response and recovery times when compared to that of thick films with long-term baseline stability. This single step process with low temperature growth conditions is compatible with direct deposition onto cost-effective and flexible substrates for widespread applications.