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

We present a pulsed laser deposition system that can monitor growth by simultaneously using in situ optical spectroscopic ellipsometry (SE) and reflection high-energy 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 SrTiO₃ (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.