Synergistic bandgap and heterojunction engineering in YbSnO thin films for high-performance self-powered solar-blind photodetection

Exploring semiconductor materials with suitable bandgaps and chemical stability is crucial for constructing solar-blind ultraviolet (SBUV) photodetectors with high stability, high responsivity, and high detectivity. However, the scarcity of suitable material systems has significantly hindered further breakthroughs in device performance. Rare-earth oxide Yb2O3, with its wide intrinsic bandgap (∼4.9 eV) and high dielectric constant, is theoretically promising for SBUV detection. Nevertheless, its practical application has been limited by an excessively large bandgap and poor electrical conductivity. Herein, we propose a synergistic strategy combining bandgap engineering and a double heterojunction design to fabricate a p-Gr/i-YbSnO/n-SiC photovoltaic-type SBUV photodetector. The active YbSnO film was realized by co-sputtering SnO2 into Yb2O3, which effectively narrows the bandgap to 4.42 eV and redshifts the absorption onset to 280 nm. By integrating monolayer graphene (Gr) as a transparent top electrode, a p-Gr/i-YbSnO/n-SiC double heterojunction was constructed. Leveraging the dual built-in electric fields, the device achieves remarkable self-powered performance under 255 nm illumination: an open-circuit voltage of 0.33 V, a responsivity of 18.41 mA/W, an external quantum efficiency of 8.96%, and a high specific detectivity of 2.31 × 1012 Jones, along with a rejection ratio (R255 nm/R340 nm) of 282. This work achieves precise bandgap control of rare earth oxide, significantly optimizes the device performance of Yb2O3-based semiconductors for SBUV detection, and provides key technical support for the practical application of such materials in miniaturized and integrated optoelectronic chips.