INV-13074
Traditional IR detectors based on semiconductor photon-detectors need cryogenic cooling, making them bulky, costly and inconvenient to use. Uncooled IR thermal detectors based on bolometric principle have been recently developed, which are much smaller, lighter, cheaper and power-efficient, making them good alternatives to semiconductor detectors. However, relatively slow response time and poor detection limit are the main obstacles for uncooled thermal detectors to rival traditional semiconductor detectors.
Nanoelectromechanical systems (NEMS) are devices that integrate electrical and mechanical functionality on the nanoscale. They are seen as the next miniaturization step from microelectromechanical systems, or MEMS devices. These systems can be used for a variety of applications, including chemical, physical, and bio-sensors, RF communications, and accelerometers. Existing NEMS systems, which have typically used thick, heavy, top metal electrodes, have been limited in overall performance, including sensitivity, limit of detection, and detection speed.
A group of Northeastern University inventors address these challenges towards the development of a high performance, ultra-fast, high resolution and low limit of detection IR/THz uncooled detector by introducing a temperature sensitive aluminum nitride (AlN) nano-plate resonator (NPR) integrated with an efficient IR/THz radiation absorber. The invented IR/THz detector consists of two components: the core element is an AlN nano-plate (10s nm thick) resonator efficiently excited in a contour-mode of vibration by piezoelectric transduction, and the other is an integrated absorber on top of the AlN NPR, which could be made by any IR/THz radiation absorbing materials/structures (ie. single wall carbon nanotube forest, Silicon Nitride, graphene or metamaterial IR/THz absorber).
When the device is exposed to IR/THz radiation, the power at specific targeted wavelengths is absorbed in the resonant core of the nano-mechanical device causing a temperature increase. Thanks to the high temperature coefficient of frequency of the AlN resonator (~100ppm/K can be achieved), a frequency shift can be readily detected. Compact and low-power CMOS circuits can be used as direct frequency read out due to the high electromechanical performance of the resonant structure (quality factor Q ~ 2000 and electromechanical coupling coefficient kt2 ~ 2%).