Dominant ultraviolet light emissions in packed ZnO columnar homojunction diodes

The growth of Sb-doped p-type ZnO∕Ga-doped n-type ZnO homojunction on Si (100) substrate by molecular beam epitaxy led to closely packed vertical ZnO columns with lateral diameters ranging from 100to400nm. Mesa structures were defined and Ohmic contact of both n-type ZnO and p-type ZnO was realized with Au∕Ti and Au∕NiO, respectively. I-V and C-V curves present typical electrical properties of a diode, indicating that reliable p-type ZnO was formed. Electroluminescence shows dominant ultraviolet emissions with insignificant deep-level related yellow/green band emissions at different drive currents from 60to100mA at room temperature.