Fabrication of Schottky barrier diodes using H2O2-treated non-polar ZnO 101¯0 substrates

Non-polar single crystal ZnO 101¯0 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 101¯0 planes were broadened with increase in H2O2 treatment time. Grain structures were clearly observed on the surfaces of ZnO 101¯0 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 101¯0 substrates without H2O2 treatment were ohmic. The J-V characteristics of Pd/ZnO2/ZnO/Al structures using ZnO 101¯0 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 101¯0 plane was estimated to be 0.92 eV.