Martin Thuo, North Carolina State University: "Synthesis and Guided Self-assembly of Tunable Bandgap Semiconductor Arrays"  (Host: Brock)

Mixed bandgap and bandgap tunability in semiconductors is critical in expanding their use. Composition alterations through single-crystal epitaxial growth and the formation of multilayer tandem structures are often employed to achieve mixed bandgaps, albeit with limited tunability. Herein, self-assembled one-dimensional coordination polymers provide facile synthons and templates for graphitic C-doped mesoporous oxides, gC-β-Ga2O3 or gC-In2O3, via controlled oxidative ligand ablation. These materials have mixed bandgaps and colors, depending on the amount of gC present. The carbon/oxide interface leads to induced gap states, hence, a stoichiometrically tunable band structure. Structurally, a multiscale porous network percolating throughout the material is realized. The nature of the heat treatment and the top-down process allows for facile tunability and the formation of mixed bandgap metal oxides through controlled carbon deposition. As proof of concept, gC-β-Ga2O3 was utilized as a photocatalyst for CO2 reduction, which demonstrated excellent conversion rates into CH4 and CO. Besides catalysis, we extend this approach into a directed self-assembly to produce hierarchical semiconductors arrays that translate to rectifiers (diodes), gates (transistors) and optical devices. These latter devices allow us to extrapolate into frugal post-Moore’s law devices.

Biography: Martin Thuo is a Professor in the Departments of materials science & engineering at NCSU. He was the Schafer 2050 professor at Iowa state University in the department of Materials Science & engineering and in Electrical and Computer engineering. Prior to this, he was a Mary-Fieser (2009-2011) and NSEC (2011-2013) Fellow at Harvard University under Prof. George M. Whitesides. He is the recipient of several awards like the ACS nano rising star, Akinc excellence in research award, Lynn-Anderson research excellence award, Black & Veatch faculty fellowship, among others. He is a co-host of the ICAN-X talks and serves on the boards of various journals. His research interests encompass the general theme of frugal innovation through simplicity and surface thermodynamics.