Optical and microstructural properties of p-type SrCu₂O₂: First principles modeling and experimental studies

In this paper, we report first principles calculations and experimental studies of the optical and microstructural properties of both bulk and thin films of SrCu₂O₂. Polycrystalline SrCu₂O₂ films were grown by a conventional Pulsed Laser Deposition method in a flowing oxygen environment on corning glass 7059 and silicon substrates. Several characterization techniques, including X-ray diffraction (XRD), Fourier Transform IR (FTIR), Raman, spectroscopic ellipsometry, reflectance/transmission spectrophotometry and Atomic Force Microscopy have been used for the investigation of the microstructural and vibrational properties of both bulk and thin films of SrCu₂O₂. XRD shows that bulk SrCu₂O₂ is polycrystalline and assumes the pure tetragonal phase of SrCu₂O₂. The vibrational properties of the tetragonal phase of SrCu₂O₂ have been inferred from Raman and FTIR spectroscopies and for the first time both Raman and IR active modes have been assigned. The bulk polycrystalline SrCu₂O₂ optical band gap determined from spectroscopic ellipsometry was 3.34 ± 0.01 eV. XRD results confirmed that pure non-textured polycrystalline phase SrCu₂O₂ thin films with a smooth surface can be grown by PLD at low temperature (300 °C).