In this study, we fabricated an AlN-based Schottky photodetector by thermal evaporation technique using commercial AlN/n-Si heterojunction which was fabricated by hydride vapor phase epitaxy. Thus, Au/Ti/AlN/n-Si heterostructure was obtained and tested for photodetector applications for various light power densities from 20 mW/cm2 to 100 mW/cm2 by I–V characteristics. Various parameters of heterostructure were extracted by thermionic emission theory, Norde and Cheung methods to clear the electrical properties of the Au/Ti/AlN/n-Si. Photodetection parameters such as responsivity, photosensitivity, and specific detectivity values were also studied depending on the changing light power density. The Au/Ti/AlN/n-Si photodetector revealed 1.36 A/W responsivity and 7.99 × 109 Jones specific detectivity values. The photoresponse time was investigated by light on-off transient measurements. The Au/Ti/AlN/n-Si photodetector exhibited fast and linear photoresponse to the illumination. The photocapacitance and photoconductance properties of the Au/Ti/AlN/n-Si photodetector were also studied. The results highlighted that Au/Ti/AlN/n-Si photodetector can be a good candidate for fast-response photodetection applications.