The growing demand for scalable solar-blind image sensors with remarkable photosensitive properties has stimulated the research on more advanced solar-blind photodetector (SBPD) arrays. In this work, the authors demonstrate ultrahigh-performance metal-semiconductor-metal (MSM) SBPDs based on amorphous (a-) Ga 2 O 3 via a post-annealing process. The post-annealed MSM a-Ga 2 O 3 SBPDs exhibit superhigh sensitivity of 733 A/W and high response speed of 18 ms, giving a high gain-bandwidth product over 10 4 at 5 V. The SBPDs also show ultrahigh photo-to-dark current ratio of 3.9 × 10 7 . Additionally, the PDs demonstrate super-high specific detectivity of 3.9 × 10 16 Jones owing to the extremely low noise down to 3.5 fW Hz −1/2 , suggesting high signal-to-noise ratio. Underlying mechanism for such superior photoelectric properties is revealed by Kelvin probe force microscopy and first principles calculation. Furthermore, for the first time, a large-scale, high-uniformity 32 × 32 image sensor array based on the post-annealed a-Ga 2 O 3 SBPDs is fabricated. Clear image of target object with high contrast can be obtained thanks to the high sensitivity and uniformity of the array. These results demonstrate the feasibility and practicality of the Ga 2 O 3 PDs for applications in solar-blind imaging, environmental monitoring, artificial intelligence and machine vision.
Two-dimensional (2D) materials with high carrier mobility and tunable magnetism are in high demand for nanoelectronics and spintronic applications. Herein, we predict a novel two-dimensional monolayer KTlO that possesses an indirect band gap of 2.25 eV (based on HSE06) and high carrier mobility (1.86×10 3 cm 2 V -1 s -1 for electron and 2.54 ×10 3 cm 2 V -1 s -1 for hole) by means of ab initio calculations. KTlO monolayer has a calculated cleavage energy of 0.56 J m -2 , which suggests exfoliation of bulk material as viable means for the preparation of mono-and few-layer materials. Remarkably, the KTlO monolayer suggests tunable magnetism and half-metallicity with hole doping, which are attributed to the novel Mexican-hat-like bands and van Hove singularities in its electron structure. Furthermore, monolayer KTlO exhibits moderate optical 2 absorption over visible light and ultraviolet region. The band gap value and band characteristics of monolayer KTlO can be strongly manipulated by biaxial and uniaxial strains to meet the requirements of various applications. All these novel properties render monolayer KTlO a promising functional material for future nanoelectronics and spintronic applications.
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