Physics Colloquium - Spring 2013
I.M. Dharmadasa - Photovoltaic Technology; Present, Future & Applications
Speaker: I.M. Dharmadasa , Sheffield Hallam University
Abstract: This presentation first introduces photo-voltaic (PV) technology for beginners and focuses on advances in thin film solar cells. By concentrating on CdS/CdTe solar cells fabricated using electroplated semiconductors, materials and device issues are presented and discussed. Examples of naturally grown and uni-directional nano- and micro-rod type materials are given and discussed. Next generation solar cells based on graded bandgap solar cells utilising nano- and micro-rod type materials are presented. After a brief discussion on applications, speaker's designing, piloting, monitoring and replication experience of "Solar Village" project is presented.
Sung Seok Ambrose Seo - Pulsed laser deposition using dual in-situ monitoring techniques: Addressing a few challenging problems in complex oxide thin-films and heterostructures
| When |
Sep 13, 2013
from 03:00 PM to 04:00 PM |
|---|---|
| Where | Natural Science 102 |
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Speaker: Sung Seok Ambrose Seo, University of Kentucky
Abstract: In this talk, I will introduce a pulsed laser deposition system that can monitor the growth of complex oxide thin-films and heterostructures by simultaneously using in situ optical spectroscopic ellipsometry (SE) and reflection high-energy electron diffraction (RHEED). While the RHEED precisely monitors the number of monolayers and surface structure during the deposition, the SE measures the optical spectra of the samples simultaneously. The thin-film thickness information obtained from RHEED facilitates the SE modeling process, which allows extracting the in situ optical spectra, i.e., the dielectric functions of thin films during growth. The in situ dielectric functions contain indispensable information about the electronic structure of thin films. I will show a couple of examples of thin films and heterostructures that our research group has recently studied by using this technique: 1) Monitoring polar/non-polar (LaAlO3/SrTiO3) heterointerfaces and real-time evolution of electron-doped interfacial states, 2) Growing and optimizing the growth conditions of epitaxial iridate (Sr2IrO4, Nd2Ir2O7, and so on) thin films on various substrates and their electronic structures as a function of lattice-strains.