Materials Science & Engineering Colloquium
Date: December 11, 2015 from 11:00 am to 12:00 pm EST
Location: Columbia University
Morningside Campus
Room 214 S.W. Mudd
Contact: For further information regarding this event, please contact Chris A. Marianetti by sending email to chris.marianetti@columbia.edu or by calling 212-854-9478.
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The key role of surface in semiconductor nanostructures

for photovoltaics and sensing applications

 

S. Mirabella

 

CNR-IMM MATIS and Universita di Catania, Dip. Fisica e Astronomia,

Via S. Sofia 64, 95123 Catania, Italy

mirabella@ct.infn.it

 

In the current nanotechnology age a countless amount of "small and smart" solutions are investigated and proposed in real devices for a variety of applications, such as photovoltaics, sensing, catalysis, security, environment, biomedical area ... The exploitation of nanostructures (NS) usually benefits from enhanced surface over volume ratio and from quantum confined effects arising at the nanoscale. Still, surface states and interface defects quite often overwhelm the previous effects and ask to be comprehended in details for a full utilization of NS. In this talk I'll give few examples of surface/interface effects in semiconductor NS (Si and Ge QDs, ZnO and NiO low-cost NS) applied to photovoltaics and sensing.

The light absorption in Si and Ge NS embedded in insulators will be presented, evidencing whether and to which extent the quantum confinement effect influences the light-matter interaction. An ideal size tuning of the optical bandgap is achieved only if Ge quantum dots have thin and defect-free Ge/SiO2 interface. Indeed, an unprecedented high absorption efficiency, ten times larger than in the bulk, is obtained for smaller and well-ordered Ge QDs in a superlattice approach.

Despite the huge potential in disposable sensors, low-cost NS of transition metal oxides (TMO) often lack reproducibility and stability because of the growth method. The growth mechanism of ZnO nanorods and nanowalls by means of chemical bath deposition will be presented and modeled, as well as the surface states responsible for UV- and pH- sensing will be evidenced. Finally, a facile synthesis on plastic substrate of a large surface area, NiO NS will be described and applied as a high sensitivity, non enzymatic glucose sensor.

BIO: SALVO MIRABELLA (Researcher ID: E-4672-2010) received his Laurea (1999) and PhD (2003) in Physics from University of Catania (Italy). Since 2003 he is a staff researcher, now at CNR-IMM. His activity is mainly experimental, focusing on semiconductor nanostructures for Photovoltaics, Smart Sensing and Microelectronics (light absorption in Si or Ge quantum structures, sunlight-energy conversion, low-cost ZnO nanostructures, biosensing, point-defects and dopants in Si and Ge, ion beam modification of materials). Since 2000 Salvo contributed to more than 140 papers on ISI scientific journals, holding an H- factor of 26 (Google Scholar). He wrote a review paper on B diffusion in Si and Ge, holds one patent on point-defect engineering, co-edited 1 book (Nanotechnology and Photovoltaics Devices: Light Energy Harvesting with Group-IV Nanostructures, Pan Standford Publishing), co-authored 3 book chapters (with CRC-T&F group, and Pan Stanford Publishing), co-organized 3 international scientific conferences and symposia, and gave 15 invited talks.