Understanding and controlling the effects of trap sites in ZnO semiconductors are crucial for optimizing device performance and enabling various technological applications. To passivate the trap sites, the N atoms are incorporated into polycrystalline ZnO thin films via a plasma nitridation (PN) process using NH3 3 gas. The results show that the contact resistivity, sheet resistance, and transfer length of the ZnO photodetector are improved after the PN treatment. The photo-to-dark current ratio (PDCR) and responsivity values increase from 42.52 to 103.19 and from 344.36 A/W to 5727.63 A/W, respectively, after the PN treatment. This improvement in photodetector properties is attributed to the introduced N atoms, which effectively reduce the trap sites in the ZnO thin film. This PN treatment technology has the potential to improve device performance in both electronic and optoelectronic applications.