Such switches will play an important role in various NEMS deveices, sensors, NEM-CMOS hybrid integrated circuits, and ultra-low-power applications.
The search for an ideal switching device for ultra-low power applications has led to the exploration of novel micro/nanoelectromechanical systems (M/NEMS). M/NEMS devices have been known for its superior performance, such as ideally abrupt switching with zero off-state leakage, suitability for hard and extreme environments, and very small footprints.
The applied electric field electro-mechanically moves the NEMS switch’s suspended element, making physical contact with the switch’s counterpart and creating the conducting channel as a result. However, the greatest barrier to their practical usage in low-power integrated circuits is an unacceptably high switching voltage of NEMS switches.
To realise NEMS switches for ultra-low power applications, the thickness of movable suspended material thickness has to be lowered, and the switch contact adhesion in the ON state must be overcome to reach the OFF state. The research team led by Dr Manoharan Muruganathan (Former Senior Lecturer) and Professor Hiroshi Mizuta at the Japan Advanced Institute of Science and Technology (JAIST) proposed graphene-based NEMS switch research for this purpose.
Although the graphene monolayer is now the thinnest material in existence, the switching voltage in a NEMS switch is directly proportional to the thickness of the suspended beam. Additionally, the ON state of graphene displays cubic mechanical restoring force, which is essential to prevent stiction. Its research team pursued a graphene NEMS switch based on a doubly-clamped suspended graphene beam with a hexagonal boron nitride (hBN) contact at the switching terminal because of this special property.
Graphene-to-hBN binding strength is low due to its van der Waals (vdW) bonding nature, which will overcome the stiction issue of NEMS switches says the researcher Dr Ngoc Huynh Van of Technical University of Denmark. Based on the unique choice of materials and NEMS switch design, they have demonstrated sub-0.5 V switching characteristics with more than 50,000 hot-switching cycles of operation. Moreover, these NEMS switches exhibit excellent switching characteristics, such as ~5 mV/dec switching slope, nearly-zero hysteresis, and >105 ON/OFF ratio, which meets the mainstream CMOS technology requirements.
These NEMS switches will play a vital role in various NEMS devices, sensors, NEM-CMOS hybrid integrated circuits, and ultra-low-power applications. [APBN]
Source: Japan Advanced Institute of Science and Technology