We have fabricated and characterized plasmonic terahertz detectors that integrate a voltage controlled planar barrier with
a grating gated GaAs/AlGaAs high electron mobility transistor. These detectors exhibit a narrowband, tunable
plasmonic response. Substantially increased responsivity is achieved by introducing an independently biased, narrow
gate that produces a lateral potential barrier adjacent to the drain when biased to pinch-off. DC electrical characterization
in conjunction with bias-dependent terahertz responsivity and time constant measurements indicate that a hot electron
bolometric effect is the dominant response mechanism over a broad range of experimental conditions. The temperature
dependence of the bolometric response is consistent with the energy relaxation time and absorption coefficient of a
2DEG. Rectification resulting from non-linear current-voltage characteristics also appears to contribute to the response.
Additionally, we have begun investigating the operation of this device with the full grating gate biased to pinch-off to
produce many detection elements in series.