It is demonstrated that moderate oxygen vacancies can greatly improve the photo-responsive performance of Zinc oxide (ZnO) nanoparticles thin film/p-Si heterojunctions. The ZnO nanoparticles thin film/p-Si heterojunctions shows a stable, repeatable photo response at 365 nm or 900 nm. Under 900 nm of 0.1 mWcm ⁻² the sensitivity of device reaches an excellent value of 1.2 × 10 ⁶ cm ² /W, with outstanding detectivity of 3.6 × 10 ¹² cmHz ^1/2 W ⁻¹ and ultrahigh responsivity of 3.5 AW ^-1 at −2 V, and a fast response speed with rising time (∼ms). The comprehensive properties of present device are significantly better than those reported ZnO thick film/Si heterojunctions and even compared with that of some new 2D nanomaterials/Si heterojunctions in all aspects of performance, achieving an optimal balance among all the critical features. The excellent performance of ZnO nanoparticles thin film/p-Si heterojunctions may be attributed to rising Fermi level of ZnO nanoparticles thin film due to moderate oxygen vacancies, the excellent optical absorption characteristics of ZnO nanoparticles thin film and the interface effect between ZnO nanoparticles thin film and Si. This high-performance heterojunctions photodetector should have important prospects for practical applications, and the integration of such metal oxide nanostructures with traditional Si semiconductor would open up great opportunities for next-generation optoelectronic devices.

Synthesizing pure phase Ba₃Si₆O₉N₄ by the conventional solid-state reaction method is challenging because of easily formed secondary phase Ba₃Si₆O₁₂N₂ showing similar crystal structure. In this work, an alternative low temperature synthesis method is presented, and a series of green to blue emitting (Ba, Sr)₃Si₆O₉N₄: Eu²⁺ phosphors were prepared by a mechanochemical activation route. Variations in photoluminescence properties and crystal structure, as induced by the change in phosphor composition, were investigated. Under ultraviolet-light excitation, Ba₃Si₆O₉N₄: Eu²⁺ phosphor exhibited a strong narrow green emission at 518 nm and simultaneously a weak emission at 405 nm, which are ascribed to different Eu/Ba sites in Ba₃Si₆O₉N₄ lattice proved by Density Functional Theory (DFT) calculations. A continuous green to blue emission in (Ba, Sr)₃Si₆O₉N₄: Eu²⁺ phosphors could be achieved by tuning the crystal structure and local coordination environment acting on Eu²⁺ with Sr/Ba substitution. More Sr/Ba substitution improved thermal quenching and resulted in a different characteristic of emission peak shift upon increasing the temperature.