High-performance and ultra-sensitive ultraviolet photodetector based on surface passivated α-Fe2O3 thin film

Abstract

Nanostructured α-Fe2O3 is a versatile material and has attracted extensive attention due to its promising electrochemical and photoelectrochemical properties, which are widely investigated in water splitting, photoelectrochemical devices, gas sensors, and catalysis. Moreover, its band gap (Eg = 2.0 eV) allows it to absorb visible light, but due to poor charge carrier mobility, ultrafast recombination of the photo-generated carriers, and surface oxygen vacancy defects its application as a photodetector got restricted. Herein with a surface passivated α-Fe2O3 film deposited on the glass substrate, the ultraviolet photodetector is demonstrated. The surface passivated photodetector is sensitive to ultraviolet light, showing a substantial enhancement in the photo-responsivity of 1.41 A/W, the external quantum efficiency of 515%, the photo-sensitivity of 1650%, and a reduction in response time of 0.06 ms (for 340 nm at a bias of +30 V) as compared with the device before surface passivation (0.228 A/W, 83%, 34%, and 1.6 ms), respectively. These improved properties are observed due to the suppression of surface defects via surface passivation, which increases free carrier concentration transport across the film. The surface passivated α-Fe2O3 thin film-based photodetector with high photo-responsivity, photo-sensitivity, high speed, and ultraviolet photoresponse is promising for practical applications, and this platform opens up new avenues for the development of low-cost, and highly efficient ultraviolet photodetectors.