Structural and optical properties of SrCu2O2 films deposited on sapphire substrates by pulsed laser deposition

We deposited SrCu2O2 (SCO) films on sapphire (Al2O3) (0 0 0 1) substrates by pulsed laser deposition. The crystallographic orientation of the SCO thin film showed clear dependence on the growth temperature. X-ray diffraction (XRD) and transmission electron microscopy (TEM) analysis showed that the film deposited at 400 °C was mainly oriented in the SCO [2 0 0] direction, whereas when the growth temperature was increased to 600 °C, the SCO film showed a dominant orientation of SCO [1 1 2]. The SCO film deposited at 500 °C was obvious polycrystalline, showing multi peaks from (2 0 0), (1 1 2), and (2 1 1) diffraction in the XRD spectrum. The SCO film deposited at 600 °C showed a band gap energy of 3.3 eV and transparency up to 80% around 500 nm. The photoluminescence (PL) spectra of the SCO films grown at 500 °C and 600 °C mainly showed blue-green emission, which was attributed to the intra-band transition of the isolated Cu+ and Cu+–Cu+ pairs according to the temperature dependent-PL analysis.

► SrCu2O2 (SCO) films were deposited on Al2O3 (0 0 0 1) by pulsed laser deposition.
► The orientation of the SCO film strongly depends on the growth temperature.
► The SCO film deposited at 600 °C showed transparency of 80% at 500 nm.
► The blue-green emission was attributed to the isolated Cu+ and Cu+–Cu+ pairs.