Sung Seok Ambrose Seo
University of Kentucky
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.