Photodetectors based on solution-processed active materials, such as colloidal nanocrystals (NCs), have emerged as promising candidates for the next generation of infrared sensing devices. However, these materials suffer from weak light absorption efficiency and poor electrical conductivity due to hopping transport. Here, we integrate HgTe NCs into plasmonic resonators and exploit spoof surface plasmon to enhance NC film absorption in the mid-wave infrared. We show that coupling the plasmonic resonator with the NC film improves the device's performance effectively, with a specific detectivity reaching 8x109 Jones at 80 K, while the responsivity is 0.25 A/W at 200 K. Moreover, the device configuration allows us to tune the carrier density by simply applying a gate bias, which leads to an increase of the photocurrent to dark current ratio up to a factor of 20.