SOI-based micro-mechanical terahertz detector operating at room-temperature and atmospheric pressure

We present a micro-mechanical terahertz (THz) detector fabricated on a silicon on insulator substrate and operating at room-temperature. The device is based on a U-shaped cantilever of micrometric size, on top of which two aluminum half-wave dipole antennas are deposited. This produces an absorption extending over the ~2 - 3.5 THz frequency range. Due to the different thermal expansion coefficients of silicon and aluminum, the absorbed radiation induces a deformation of the cantilever, which is read out optically using a 1.5 mu m laser diode. By illuminating the detector with an amplitude modulated, 2.5 THz quantum cascade laser, we obtain, at room-temperature and atmospheric pressure, a responsivity of ~ 1.5 x 10(8) pm W-1 for the fundamental mechanical bending mode of the cantilever. This yields noise-equivalent-power of 20 nW/root Hz at 2.5 THz. Finally, the low mechanical quality factor of the mode grants a broad frequency response of approximately 150 kHz bandwidth, with a thermal response time of ~2.5 mu s. Published under an exclusive license by AIP Publishing.

Automated summary

The study introduces a micro-mechanical terahertz detector fabricated on a silicon on insulator substrate, operating at room temperature. It achieves a high responsivity with a broad frequency response and fast thermal response time.