Pulsed laser deposition with simultaneous in situ real-time monitoring of optical spectroscopic ellipsometry and reflection high-energy electron diffraction

Abstract

We present a pulsed laser deposition (PLD) system that can monitor growth by simultaneously using in situ optical spectroscopic ellipsometry (SE) and reflection highenergy electron diffraction (RHEED). The RHEED precisely monitors the number of thin-film layers and surface structure during the deposition and 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. We demonstrate the performance of this system by growing LaMnO 3+δ (LMO) thin-films on SrTiO 3 (001) substrates. By using in situ SE and RHEED simultaneously, we show that real-time thickness and dielectric functions of the LMO thin-films can be effectively extracted. The simultaneous monitoring of both optical SE and RHEED offers important clues to understand the growth mechanism of atomic-scale thin-films. a)

Reversal of the Lattice Structure inSrCoOxEpitaxial Thin Films Studied by Real-Time Optical Spectroscopy and First-Principles Calculations

“…This observation underscores an unconventional but important topotactic phase transformation involving redox reaction in a sample, which is unique for epitaxial TMO thin films which contain multivalent cations. The evolution of the electronic structure during reversible redox reactions in the material was directly monitored using a real-time spectroscopic ellipsometer, while simultaneously controlling the oxygen partial pressure (P(O 2 )) and temperature in a vacuum chamber [22]. This technique enables us to study fundamental optical properties, during the redox activity and associated valence state changes in oxide thin films [22,23].…”

Anisotropic electronic properties of a-axis-oriented Sr2IrO4 epitaxial thin-films

“…17 Optimal growth parameters are oxygen partial pressure (P O2 ) of 10 mTorr, substrate temperature of 700 ˚C, and laser (KrF excimer, λ = 248 nm) fluence of 1.2 J/cm 2 . We have monitored the thin film growth using RHEED, which shows a "layer-bylayer + island" growth mode, presumably due to the large surface energy of the film.…”

Optoelectronics

“…Recently, a simultaneous use of both RHEED and spectroscopic ellipsometry in a PLE system was demonstrated, as shown in Figure 12.20 (Gruenewald, Nichols, & Seo, 2013). By probing the electronic structure in real-time, this system can yield indispensable information about the complicated growth mechanisms of oxide thin films.…”