Zinc oxide (ZnO) is a versatile compound or metal oxide with a wide range of applications across various industries such as electronics, optoelectronics, and gas sensors, etc. A simple hydrothermal method was used to synthesize ZnO flower-like structures in this study. The synthesized ZnO structures were analyzed by X-ray diffractometer (XRD) and scanning electron microscope (SEM). We used ZnO structures as an interfacial layer for a Schottky-type silicon-based photodetector. While Au and Al metals were employed as metallic and ohmic contacts, respectively, p-Si was utilized as a semiconductor and substrate. Thus, Au/ZnO/p-Si sandwich was successfully fabricated and tested by current–voltage (I–V) measurements under dark and various light power illumination densities from 10 mW/cm2 to 150 mW/cm2 as well as the various wavelengths in the case of same power. The I–V characteristics were used to determine the diode and photodetection parameters. The fabricated heterostructure exhibited 77.51 mA/W responsivity, 1.30 × 1010 Jones specific detectivity, and 26.33% external quantum efficiency (EQE) values.