High figure-of-merit NEMS thermal detectors based on 50-nm thick AlN nano-plate resonators

Abstract

This paper reports on the demonstration of ultrafast (thermal time constant, τ ∼166 μs) and high resolution (noise equivalent power, NEP ∼549 pW/Hz1/2) thermal detectors based on high quality factor 50-nm thick aluminum nitride (AlN) piezoelectric resonant nanoplates. Here we show that by employing nanoscale (30 nm) aluminum anchors, both high thermal resistance (Rth ∼1.1 × 106 K/W) and high quality factor (Q ∼1000) can be achieved in greatly scaled AlN nanoplate resonators. Furthermore, the absorptance of such ultrathin AlN resonators was characterized, in mid-wavelength infrared region showing an average absorptance of ∼36% from 2.75 μm to 6.25 μm. These unique features were exploited for the experimental demonstration of AlN NEMS resonant thermal detectors with greatly reduced thermal capacitance and over doubled figure of merit [FoM = 1/(NEP × τ)] compared to what was previously achieved by the same technology.