Research

  • Multiferroic materials and transducers

    • Magnetic Nano-Ring and Single Domain

      We have patterned magnetic nano-ring and single domain structures of Ni on (011) PMN-PT substrate, and used MFM and X-PEEM technique to characterize the magnetic domain movement in patterned Ni nanostructures. We have achieved a permanent 90° rotation in the magnetization direction of patterned rings using only electric field-induced magnetoelastic anisotropy. Using X-PEEM we have Read More »
    • Giant Tunable Piezoelectric Remanent Strain and its Application on ME-RAM

      We have demonstrated a Ni/PMN-PT ME heterostructure providing an electric-field-induced switching between two reversible and permanent magnetic easy axes perpendicular to each other. The tunable remanent strain defines the initial magnetoelastic anisotropy while the giant strain hysteresis reversibly and permanently reorients the magnetization state. This experimental data were used to design a ME-MRAM with MTJ Read More »
    • Giant piezoelectric strain hysteresis and novel ferroelectric properties of (011) [Pb(Mg1/3Nb2/3)O3](1-x)-[PbTiO3]x (PMN-PT, x≈0.32) single crystals

      The ferroelectric (011) [Pb(Mg1/3Nb2/3)O3](1-x)-[PbTiO3]x (PMN-PT, x≈0.32) single crystals show two giant reversible and stable remanent strain states and tunable remanent strain properties are achieved by properly reversing  the electric field from the depolarized direction. The unique piezoelectric strain response, especially along the [100] direction, mainly stems from the non-180º ferroelectric polarization  reorientation in the rhombohedral Read More »
  • Piezoelectric MEMS Resonators and Transducers

    • Aluminum Nitride RF MEMS

      Aluminum Nitride (AlN) piezoelectric nano-plate NEMS resonant devices that can address some of the most important challenges in the areas of physical, chemical and biological detection and can be simultaneously used to synthesize high-Q reconfigurable and adaptive radio frequency (RF) resonant devices. By taking advantage of the extraordinary transduction properties of AlN combined with the Read More »
  • Advanced Micro-/Nano-scale Processing Technologies

    • Tessellated Silicon-Structures for Monocentric Imagers

      Compared with conventional planar optical image sensors, a curved focal plane array can simplify the lens design and improve the field of view. In this paper, we introduce the design and implementation of a segmented, hemispherical, CMOS-compatible silicon image plane for a 10-mm diameter spherical monocentric lens. To conform to the hemispherical focal plane of Read More »
    • Self-Aligned T-Gate High-Purity Semiconducting Carbon Nanotube RF Transistors

      Carbon nanotube RF transistors are predicted to offer good performance and high linearity when operated in the ballistic transport and quantum capacitance regime; however, realization of such transistors has been very challenging. In this paper, we introduce a self-aligned fabrication method for carbon nanotube RF transistors, which incorporate a T-shaped (mushroom-shaped) aluminum gate, with oxidized Read More »
    • Atomic layer deposition of Pb(Zr,Ti)Ox on 4H-SiC for metal-ferroelectric-insulator-semiconductor diodes

      Atomic layer deposited (ALD) Pb(Zr,Ti)Ox (PZT) ultra-thin films were synthesized on an ALD Al2O3 insulation layer on 4H-SiC substrate for metal-ferroelectric-insulator-semiconductor (MFIS) device applications. The as-deposited PZT was amorphous but crystallized into a perovskite polycrystalline structure with a preferred [002] orientation upon rapid thermal annealing (RTA) at 950 C. The capacitance-voltage and current-voltage characteristics of Read More »