High-Resolution Mapping of Local Photoluminescence Properties in CuO/Cu2O Semiconductor Bi-Layers by Using Synchrotron Radiation

Abstract

The quality of a semiconductor, which strongly affects its performance, can be estimated by its photoluminescence, which closely relates to the defect and impurity energy levels. In light of this, it is necessary to have a measurement method for photoluminescence properties with spatial resolution at the sub-micron or nanoscale. In this study, a mapping method for local photoluminescence properties was developed using a focused synchrotron radiation X-ray beam to evaluate localized photoluminescence in bi-layered semiconductors. CuO/Cu2O/ZnO semiconductors were prepared on F:SnO2/soda-lime glass substrates by means of electrodeposition. The synchrotron radiation experiment was conducted at the beamline 20XU in the Japanese synchrotron radiation facility, SPring-8. By mounting the high-sensitivity spectrum analyzer near the edge of the CuO/Cu2O/ZnO devices, luminescence maps of the semiconductor were obtained with unit sizes of 0.3 μm × 0.3 μm. The devices were scanned in 2D. Light emission 2D maps were created by classifying the obtained spectra based on emission energy already reported by M. Izaki, et al. Band-like structures corresponding to the stacking layers of CuO/Cu2O/ZnO were visualized. The intensities of emissions at different energies at each position can be associated with localized photovoltaic properties. This result suggests the validity of the method for investigation of localized photoluminescence related to the semiconductor quality.

Mind the Interface Gap: Exposing Hidden Interface Defects at the Epitaxial Heterostructure between CuO and Cu2O

“…The ferromagnetism was traced back to oxygen vacancies present at the interface which introduce one localized orbital with two unpaired electrons via which the doped electrons can hop between different Cu ions connecting them ferromagnetically (double-exchange). Heterostructures of CuO and Cu 2 O have been investigated for photocatalytic H 2 evolution reactions on both nanomaterials and films. − More recently, local photoluminescence properties of CuO/Cu 2 O bilayers were assessed. , There, light emission intensity maps at photon energies of 1.5–3.3 eV were measured for samples annealed at different temperatures, yet a definite band assignment was not conclusive as the spatial resolution was limited to a few μm. Izaki et al grew a layer of CuO on top of a Cu 2 O layer and analyzed the photovoltaic (PV) properties of the stacked layers .…”