Ultraviolet Photodetector Based on Nanostructured Copper Iodide Films Deposited by Automatic SILAR Method

The paper presents the results of studies of the structure, composition and morphology of sulfur-doped copper iodide (CuI) nanostructured films deposited on glass substrates by the Successive Ionic Layer Absorption and Reaction (SILAR) method for use as functional materials for ultraviolet photodetectors (UV PD). By varying the temperature used in the deposition process, it is possible to obtain 1 m thick CuI layers with the morphology of nanoflakes (at 20 C) or with (111)-textured triangular CuI nanograins (at 30 C). By equipping these copper iodide layers with Cr/Cu thin film electrodes on both sides, we obtained UV PDs of photoconductive type. Their linear current-voltage characteristics confirmed the formation of ohmic contacts. The photoresponses of UV PDs over time were recorded and analyzed under different intensities from 0.15 mW/cm2 to 1.17 mW/cm2 of UV light with an average wavelength of 367 nm. According to the generally accepted criteria for evaluating the performance of a photodetector, the UV PD with the CuI nanoflake morphology has a higher performance and a shorter response time than that based on the nanostructured copper iodide film with triangular grains. It exhibits the photosensitivity of 170 %, the responsivity of 3 A/W, the specific detectivity of 1.2‧1011 Jones and the external quantum efficiency of 1000 %. These results are similar to those recently obtained by various research groups around the world, confirming the potential of using the UV photosensitive CuI material with nanoflake morphology obtained by the automatic SILAR method in thin-film UV sensing technology.