A research team led by Professor Chang-Beom Eom at the University of Wisconsin-Madison has found a way to create a low-voltage near-nanoscale electromechanical device by integrating a complex, single-crystal, piezoelectric material called lead magnesium niobate-lead titanate (PMN-PT) having ‘giant’ piezoelectric properties with silicon.
This innovation paves the way to advanced nanopositioning actuators, sensing technologies, energy harvesting, communications, signal processing and high-resolution three-dimensional imaging and more. PMN-PT demonstrates a ‘giant’ piezoelectric effect that can provide higher mechanical displacement when compared to other piezoelectric materials.
The integration of PMN-PT into ultra-compact devices is a major challenge to researchers. Scientists have previously used cutting, grinding and polishing techniques to produce the desired size from the bulk material, which is an error-prone method and is not suitable for producing MEMS and NEMS devices.
Eom’s research team has overcome this complexity of PMN-PT by employing microscale fabrication processes utilized in computer electronics. The team succeeded in seamlessly integrating PMN-PT into silicon. Since potential chemical reactions may occur between the components, the team layered the materials and selectively planned the positions of individual atoms. The team has incorporated an ultra-thin strontium titanate layer onto a silicon platform. The strontium titanate layer functions as a template and imitates the silicon structure. It has then added a strontium ruthenate layer and finally PMN-PT.
Eom stated that the piezoelectric material integrated with silicon demonstrates the same quality of properties as that of the bulk single crystal. The team has termed nanoscale devices made of this complex single-crystal material as ‘hyper-active MEMS’ due to their high magnitude of active control. The team has also designed a technique to fabricate piezoelectric MEMS utilizing this giant piezoelectric material.