Photoluminescence and electrical properties from CdO/Cd-nanocrystallites on Cd foil

CdO, which is an n-type II-VI semiconductor compound, plays an increasingly important role in the optoelectronic field. In this paper, CdO micro-rods have been synthesized through using Cd foil as the Cd2+ source and the substrate by a solvothermal method, which are approximately perpendicular to the substrate. Meanwhile, Cd nanocrystallites (nc-Cd) have been fabricated, which are observed to locate at the bottom of CdO micro-rods. Photoluminescence at 10 K has been measured and shown multiple peak emissions. Through analyzing the temperature-dependent photoluminescence and the Varshni formula, the peak located at ~ 487 nm has been confirmed as the emission of band gap. The peaks of ~ 501 nm and ~ 588 nm are disappeared with the increasing of temperature, which are ascribed to the emissions from Cd interstitials to valence band and excitonic transitions, respectively. The peak located at ~ 715 nm is attributed to the emission of surface defects and shows blue shift with increasing temperature. It may be due to the influence of the existence of nc-Cd located at the bottom of CdO micro-rods and/or the interface between CdO and nc-Cd. The current density vs voltage (I-V characterization) from CdO/nc-Cd on Cd foil shows the obvious rectifying effect. Through analyzing the I-V characterization, it is indicated that there are a lot of defects in the CdO to impede the performance. It is believed that through optimizing the preparation process CdO/nc-Cd on Cd foil will be potentially applied in the future optoelectronic field.