Mn-Doped XAlO3 (X = Y, Tb) Single-Crystalline Films Grown onto YAlO3 Substrates: Raman Spectroscopy Study toward Visualization of Mechanical Stress

Single-crystalline films (SCFs) of perovskites TbAlO3 (TbAP) and YAlO3 (YAP) doped with Mn ions were grown using the liquid-phase epitaxy (LPE) method on YAlO3 single-crystal (SC) substrates and investigated using Raman spectroscopy. The cross-section of the above-mentioned epitaxial structures was probed to obtain Raman signals of TbAP:Mn, YAP:Mn SCFs, and the YAP SC substrate. The undisturbed Raman signals of TbAP:Mn and YAP:Mn were recorded. For the TbAP:Mn sample, due to the difference in lattice constants between the SCF and the substrate, significant changes in the Raman spectra were observed. Over the interface between the SCF and the substrate, called the transition layer, gradual changes in the Raman spectra were observed. The changes are connected with the replacement of Tb3+ ions with Y3+ cations and are manifested as shifts of the modes assigned to translational, librational, and internal vibrations. Angular-dependent measurements of polarized spectra allowed determination of the TbAP:Mn SCF orientation in the ac plane (010). High-resolution luminescence spectra confirmed electronic transition attributed to Tb3+ cations and Nd3+ trace impurities in the YAP substrate. The Raman map recorded for the region close to the transition layer showed a shift of the Raman band at 552 cm–1 (YAP) related to the changes in the lattice constants and mechanical stress.