Fabrication of Schottky barrier diodes using H2O2-treated non-polar ZnO image substrates

Non-polar single crystal ZnO image substrates with hydrogen peroxide (H2O2) treatment were characterized and applied to Schottky barrier diodes. Formation of a ZnO2 layer with a polycrystalline structure was confirmed by 2θ scans of X-ray diffraction (XRD) measurements. Tails of the X-ray rocking curve of ZnO image planes were broadened with increase in H2O2 treatment time. Grain structures were clearly observed on the surfaces of ZnO image substrates with H2O2 treatment by an atomic force microscope, and the root mean square roughness of the ZnO2 surface was about 5 nm. The current density–voltage (J–V) characteristics of Pd/ZnO/Al structures using ZnO image substrates without H2O2 treatment were ohmic. The J–V characteristics of Pd/ZnO2/ZnO/Al structures using ZnO image substrates with H2O2 treatment time of 5 min showed good rectifying characteristics. The ideality factor n of this diode was 1.7 and the barrier height between Pd films and the ZnO2 layer on the ZnO image plane was estimated to be 0.92 eV.