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(a) Three-dimensional rendering of an atomic-force micrograph of an SSD, showing contact layout and etched trenches with the location of the 2DEG ( axis not in scale). The SSD channel is 1500 nm long and 210 nm wide, the trench width and depth are 110 nm and 130 nm, respectively. (b) characteristic at room temperature of an array of four SSDs connected in parallel, fabricated in the gap of the bow-tie antenna. (c) Self-complementary bow-tie antenna used to couple the THz radiation to the SSDs. (d) Heterostructure utilized for the SSD fabrication. The location of the 2DEG is marked by the blue dashed line.
Diagram showing the measurement setup. The THz beam generated by FELBE was focused by a parabolic mirror onto the rectenna. The THz beam was stirred through a four-mirror polarizer to rotate the polarization of 90° by a set of flip mirrors. A current source biased the rectenna and the rectified voltage was read out with a lock-in amplifier. A calibrated power meter and an aperture were also used to estimate the actual power density on the device.
Rectified-voltage output from the rectenna at 1.5 THz as a function of the SSD dc bias at room temperature (300 K). The power of the THz radiation was kept constant at . Changing the dc allows for probing the different features and nonlinearity of the rectenna. The highest sensitivity was 300 mV/mW at a bias of 100 nA.
Rectified-voltage output from the rectenna as a function of the power of the THz radiation at a temperature of 12 K with the rectenna unbiased. For power levels lower than the rectenna showed a linear response (square-law region).
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