SOI-based micro-mechanical terahertz detector operating at room-temperature

TL;DR

This paper introduces a room-temperature, SOI-based micro-mechanical terahertz detector utilizing a U-shaped cantilever and aluminum antennas, achieving high responsivity and broad bandwidth for THz detection.

Contribution

The work presents a novel micro-mechanical THz detector fabricated on SOI with integrated antennas, operating at room temperature with high responsivity and fast response time.

Findings

Responsivity of ~1.5×10^8 pm/W at 2.5 THz

Noise-equivalent-power of 20 nW/Hz^1/2

Broad frequency response of ~150 kHz bandwidth

Abstract

We present a micro-mechanical terahertz (THz) detector fabricated on a silicon on insulator (SOI) 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 $\sim 2-3.5$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 $\sim 1.5 \times 10^{8}$pm/W for the fundamental mechanical bending mode of the cantilever. This yields an noise-equivalent-power of 20 nW/Hz$^{1/2}$ at 2.5THz. Finally, the low mechanical quality factor of the mode grants a broad frequency response of approximately 150kHz bandwidth, with a response time of $\sim 2.5\mu$s.