In some example embodiments, an infrared detector may comprise a substrate; a resonator spaced apart from the substrate, the resonator absorbing incident infrared light; a thermoelectric material layer contacting the resonator and having a variable resistance according to temperature variation due to the absorbed incident infrared light; a lead wire electrically connecting the thermoelectric material layer and the substrate; a heat separation layer between the substrate and the thermoelectric material layer, the heat separation layer preventing heat from being transferred from the thermoelectric material layer to the substrate; and/or a ground plane layer preventing the incident infrared light from proceeding toward the substrate. The heat separation layer may at least reduce heat transfer from the thermoelectric material layer to the substrate. The ground plane layer may at least reduce an amount of the incident infrared light that reaches the substrate.