The surface passivation treatment of mercury cadmium telluride infrared detectors has a significant impact on the device′s dark current, which determines the device′s detection performance. In order to investigate the inhibitory effect of different growth methods of surface passivation layers on dark current, a molecular beam epitaxy system was used to grow mercury cadmium telluride material on a Si substrate. CdTe/ZnS passivation film layers were grown by magnetron sputtering and in-situ passivation methods, respectively. A variable area photovoltaic detector was prepared on HgCdTe material using semiconductor technology. By testing the dark current of devices with different passivation film layers, the relationship between zero bias resistance and area product (R₀A) and the ratio of perimeter area (p/A) was analyzed. The result shows that Si-based mercury cadmium telluride devices with magnetron sputtering growth passivation layers exhibit significant tunneling currents, while Si-based mercury cadmium telluride devices with in-situ passivation growth passivation layers can more effectively suppress surface leakage currents. By fitting the variation of the R₀A factor of the device with the PN junction area, it can be seen that devices with in-situ growth of passivation layers have better passivation effects. The preparation and testing of variable area devices can effectively and intuitively reflect device performance.