MSE Department Seminar

Nanotechnology and nanoscale fabrication techniques have held promise for a wide range of research areas. Beyond traditional microelectronics applications, a wealth of new materials, structures and devices have impacted biology, medicine, chemistry and the physical sciences. My research group, located at the Albany Nanotech Complex, leverages both small scale (200mm wafer scale and smaller) fabrication methods and large scale (300mm wafer scale) approaches to developing new technologies for biosensing and bio-inspired electronics.

Conventional rechargeable batteries are formed using slurry-cast electrodes whose random nature and porosity limits both energy density and rate performance. As a general rule, such composite electrodes, consisting of a mixture of active material, solid electrolyte, and often conductive additives exhibit power and energy limitations due to the tortuosity of the ion and electron conduction pathways and lower than ideal energy densities due to the volume and mass of the additives.

A novel potassium phospho-aluminosilicate (KPAS) glass composition is described that can be strengthened by water vapor to achieve deep compressive stress profiles. This material was initially discovered through a series of hydration experiments in which the KPAS specimen achieved a 29 micron compressive depth after being held in a 85oC, 85% relative humidity chamber for 65 days, thus exhibiting diffusivity orders of magnitude greater than comparative glasses.

Electronic defects within the band gap of semiconductor materials play critical roles in determining the efficiency and stability of their photovoltaic devices. Eliminating deleterious defects in semiconductors or passivating them during the fabrication process of solar cells has become one of the most fundamental tasks for the solar cell society.

A century of experiment and theory have produced a thorough understanding of heat conduction by phonons in simple inorganic crystals. By contrast, basic understanding of heat conduction by molecular vibrations in soft materials (amorphous and crystalline polymers, small molecule solids, and biological materials) is much less mature. Complex, disordered structures spanning multiple length scales are difficult to characterize and model.

Experimental techniques for rapid collections of materials data and holistic approaches to integrate experimental and computational data will be described with examples. Localized property measurements on composition gradients created in diffusion multiples allow high-throughput collection of several materials properties as a function of composition, in addition to phase diagrams and diffusion coefficients.

Mechanical force is an essential tool to keep our physical world running by modulating the conversion of mechanical energy into other forms of energy, such as thermal, photonic, and chemical energies. Over the past decade, mechanical force has become a powerful tool for chemists to create colors, induce reactions, and develop advanced manufacturing techniques. However, fundamental studies on the interactions and propagations of forces in soft materials still face significant challenges.

A Wigner crystal, an electron solid, is the first predicted correlated electron state, and exhibits intriguing quantum and classical phase transitions. Despite decades of research, it has been challenging to realize Wigner crystals in the quantum regime where quantum fluctuations dominate over thermal fluctuations.

Attracted by their desired functional properties, significant effort has been taken during the last two decades in the development of nano fabrication techniques for metals. A wide range of bottom-up and top-down techniques have been developed. Those techniques, however, are generally limited in some critical aspects such as material choice, geometry, and/or scalability. A highly versatile and widely used fabrication method is molding, which is generally associated with a soft state of a material.

Competition between ground states at phase boundaries can lead to significant changes in materials properties under stimuli, particularly when these ground states have different crystal symmetries. A key challenge is to stabilize and control coexistence of symmetry-distinct phases.