We pursue innovative developments in semiconductor devices using novel three-dimensional micro and nanostructures. The development of new fabrication techniques for these structures is also an important target in our study.
We are studying micro/nanomechanical structures for application to novel devices, such as high-performance sensors and highly energy-efficient logic systems. Piezoelectricity and photon-carrier interactions in compound semiconductor heterostructures are exploited to develop new electromechanical functions in these devices. We recently proposed a novel logic system based on electromechanical parametric resonators, as well as a method to control the mechanical resonance characteristics by optical carrier excitation. We also apply micro/nanomechanical systems for material characterization; the local conductance in graphene was successfully mapped with nanometer scale resolution using an integrated nano-gap probe. Novel nanofabrication techniques, such as three-dimensional (3D) electron beam lithography and block co-polymer lithography, are also being developed for fabricating 3D nanostructures.