Dual-wavelength solar blind photodetectors based on GeTiO2 vertical and lateral heterojunctions

Wide bandgap heterojunction solar blind photodetectors (SBPDs) are actively being explored to achieve widespread applications in the military and civilian fields. However, interface defects induced during the stacking process of the vertical heterostructure reduce the SBPD performance. Here, GeTiO₂ vertical and lateral heterojunction SBPDs have been fabricated by using the radio frequency magnetron sputtering strategy and exhibit obvious dual-wavelength solar-blind photoresponses. Compared to the vertical heterojunction SBPD, the GeTiO₂ lateral heterojunction SBPD has been demonstrated substantially enhanced performances including good photoresponsivity of 2.01 × 10⁻² and 4.5 × 10⁻⁴ A/W, high detectivity of 2.07 × 10¹⁰ and 5.7 × 10⁸ Jones, and large external quantum efficiency of 11.7 and 0.22 % at 213 and 254 nm due to the decreased interface defect and adjusted band arrangement. Besides, benefiting from their short response time, GeTiO₂ lateral heterojunction SBPDs successfully achieve binary-encoded information transmissions and optoelectronic logic device applications. Our work presents a feasible strategy for fabricating high-performance lateral heterojunction SBPDs, offering new insights into the design of oxide semiconductor heterostructures for developing optoelectronic applications.