Thin films of single-crystal cuprous oxide grown from the melt

We have grown thin films of cuprous oxide (Cu₂O) from the melt in a small gap between paired substrates of MgO or Al₂O₃ single crystals. The films are characterized by scanning electron microscopy, X-ray diffraction and optical spectroscopy. The thickness of the films is found to range from 16nm to 20 μn. The domain structure with dimensions of 0.1-1 mm is found and attributed to single crystals oriented into different directions. The narrow peaks in rocking curves and in azimuthal angle rotations indicate the formation of highly oriented single-crystal films. Clear peaks due to yellow, green, blue, and violet excitons are observed in optical spectra. The positions of the peaks depend on the thickness of the film, implying strain-induced shifts of the exciton levels.