Boosted Room-Temperature Dielectric and Photodetection Performance of a Heterojunction Photoresistor with Faceted ZnO Nanostructures

Faceted ZnO nanostructures were hydrothermally grown on p-Si substrates to fabricate a p-n heterojunction device, and their room-temperature dielectric and photodetection properties were systematically investigated. XRD and SEM confirmed high crystallinity (∼50 nm crystallite size) and a uniform faceted morphology (∼750 nm thick). The ZnO surface consisted of densely packed nanocrystals with well-defined hexagonal facets, which significantly enhanced the interfacial polarization and surface states. Broad photodetection tests revealed sensitivity in the 390–950 nm range, showing a particularly strong infrared response compared to the UV region and achieving up to 480% photoresponse under 100 mW illumination. The device exhibited low dark current (2.06 × 10–5 A), high photocurrent (6.14 × 10–5 A), responsivity of 16.32 A/W, specific detectivity of 3.18 × 1010 Jones, and fast rise/fall times (0.89/2.32 s). Importantly, the photoresistor demonstrated excellent stability under repeated cycling, prolonged illumination, and ambient storage, maintaining a consistent performance without degradation. These results establish a direct correlation between ZnO facet engineering and the coupled dielectric-photodetection performance, offering a cost-effective route toward high-performance photoresistors and multispectral optoelectronic devices. Owing to its high dielectric constant and low loss, the device further exhibits excellent suitability for practical photoresistor applications, combining strong dielectric functionality with efficient and stable broadband light detection.