TITLE : Molecularly-engineered inorganic nanomaterials and interfaces for novel properties.

ABSTRACT :

Integrating nanomaterials, and tailoring heterointerfaces with control over multiple properties, are crucial for many diverse applications in emerging electronics devices and systems. The first part of my talk will discuss a new class of high figure-of-merit bulk thermoelectric materials that can be used for thermal management of device packages. I will show that bulk pellets and thin films comprised of dilutely-doped nanocrystals of pnictogen chalcogenides and oxides exhibit multifold thermoelectric figure of merit increases arising from a combination of doping-induced electronic structure changes and nanostructuring. Besides nanostruturing-induced thermal conductivity decreases, we obtain unusual and simultaneous increases in electrical conductivities and Seebeck coefficients due to doping. Electron spectroscopy and density functional theory calculations show that key mechanisms include doping-induced carrier concentration control, suppression of antisite defects, and multifold increases in the density of states effective mass associated with profound changes in the electronic band structure. The second part of my talk will describe the use of molecular nanolayers to tailor chemical, mechanical, thermal and electronic properties of metal-ceramic and metal-thermoelectric interfaces germane to electronic device metallization and packaging. I will demonstrate that introducing molecular nanolayers (e.g., organosilanes, thiols, organophosphonates) at inorganic metal-oxide and metal-thermoelectric interfaces can produce remarkable multifold enhancements in interfacial mechanical strength, and thermal and electronic transport. Electron and ion beam spectroscopy, and X-ray and electron diffraction show that the property enhancements are due to nanolayer-induced alterations to the inorganic interface chemistry and structure. Key mechanisms include strong bonding, interfacial oxide scavenging, diffusion curtailment, and altered phase formation, all of which can be controlled by appropriate choice of molecular termini, length and backbone chemistry, and annealing treatments. Such molecularly-directed tailoring of interface properties should be attractive for realizing multifunctional electronics devices and energy systems.

MEETING DETAILS :

Speaker: Prof. Ganpati Ramanath

Venue: Online

Date and Time: September 24th, 2021 4:30pm-6pm