Photoluminescence Spectroscopy of Cuprous Oxide: Bulk Crystal versus Crystalline Films

Cuprous oxide (Cu2O) crystals and films of 10–65 nm thickness are investigated via electron diffraction, scanning tunneling microscopy (STM), photoluminescence (PL) spectroscopy at temperature between 100 to 300 K. While the chemical composition surface morphology both systems identical, large differences found in optical response. Bulk Cu2O shows pronounced PL peaks 620, 730, 920 nm, compatible with radiative decay free bound excitons, whereas broad asymmetric 775 850 for grown on Au(111) Pt(111) supports. The latter represent signature VO2+ VO+ defects, being inserted substrate-dependent concentrations due oxygen-poor preparation films. Despite strong VO PL, all samples show p-type conductance behavior STM spectroscopy, indicating an abundance Cu defects lattice. fact that O vacancies still govern thin-film is explained by a more efficient recombination VO- than Vcu-emission channels, as requires exciton formation first. Herein, high sensitivity low-temperature probe defect landscape dielectrics, neither reached photoelectron nor techniques demonstrated.