Development of thin-film inorganic perovskite UV photodetectors

Within the framework of the INFN-CSN5 PROVIDE experiment, we fabricated planar detectors by depositing 1-μm-thick films using radio-frequency magnetron sputtering (RF-MS). These films were grown on both commercial and in-house substrates featuring various interdigitated electrode (IDE) geometries on both rigid and flexible platforms. Our characterization revealed that key detector parameters — including an effective room-temperature resitivity ρ ≈ 107Ω cm and a mobility-lifetime product μτ ≈ 2 × 10-7cm2/V, derived from a Hecht-expression best-fit under 450 nm UV LED irradiation, remained consistent regardless of the substrate type or electrode configuration. Furthermore, we measured a responsivity of approximately 0.2 A/W for optical powers up to at 450 nm. We also prototyped optimized, fully in-house detectors consisting of thin films grown by the Firenze Unit on flexible Kapton substrates, which were equipped with Cr/Au IDEs produced via lithography and thermal evaporation by the Bologna Unit. When exposed to a 300 ps UV (355 nm) laser pulse, these devices demonstrated a fast response with a 1 ns rise time and slew rates of up to 0.14 V/ns, depending on the applied bias. These performances, comparable to reference silicon photodiodes, will possibly open the way to a new class of high-speed thin-film radiation detectors. The results will be further exploited in the near future for advanced high-energy photon and particle detection.