Photoluminescence and X-ray diffraction studies on Cu2O

Cuprous oxide (Cu2O) crystals were grown by the two-step crystallization method in air atmosphere conditions from polycrystalline thin copper foils. The method comprises two stages; in the first one the copper plates are oxidized at 1020 °C by some hours in line with its initial thickness. In the second stage, the growth of large crystalline areas is promoted by annealing the Cu2O samples at 1100 °C for long periods. Raman scattering an X-ray measurements demonstrates the existence of the single-phase Cu2O. The effects on the crystalline structure and photoluminescence (PL) response were studied as a function of the conditions used in the second stage of the synthesis method. PL spectra were taken from 10 to 180 K to define the main radiative recombination paths. Besides the near band excitonic transitions, two strong emission bands at 720 and 920 nm associated with relaxed excitons at oxygen and copper vacancies were detected. Both excitonic-vacancy bond transitions presented similar intensities that are related to the growth method. X-ray and Raman scattering measurements help to assess the samples crystalline quality.