Oxygen vacancies enhanced photoresponsive performance of ZnO nanoparticles thin film/Si heterojunctions for ultraviolet/infrared photodetector

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.