High-performance self-powered ultraviolet photodetectors based on mixed-dimensional heterostructure arrays formed from NiO nanosheets and TiO2 nanorods

Abstract

The morphology and geometry of semiconductors will affect the photoresponse performance of mixed-dimensional heterojunction photodetectors (PDs). Self-powered UV PDs based on mixed-dimensional heterostructure arrays are formed from two-dimensional NiO nanosheet arrays and one-dimensional TiO₂ nanorod arrays. The Fermi level position and carrier concentration of the NiO nanosheets can be adjusted by the thickness of each layer and film. The enhanced built-in potential field of the NiO/TiO₂ interface decreases the charge transfer resistance and the appreciated carrier transfer path improves the photogenerated carrier separation and transfer ability without external bias. The self-powered NiO/TiO₂ heterojunction device demonstrates a large responsivity of 0.86 A W⁻¹, a high detection sensitivity of 1.6 × 10¹³ Jones and a fast photoresponse time of 3 ms under weak UV light illumination.