ZnO:Sb/ZnO:Ga Light Emitting Diode on c-Plane Sapphire by Molecular Beam Epitaxy

p-type Sb-doped ZnO (ZnO:Sb)/n-type Ga-doped ZnO (ZnO:Ga) junctions were grown on c-plane sapphire substrates using plasma-assisted molecular-beam epitaxy. Mesa geometry light emitting diodes (LEDs) were fabricated using standard photolithography and lift-off process, with ohmic contacts achieved using Au/Ni and Au/Ti for top ZnO:Sb and bottom ZnO:Ga layers, respectively. Rectifying current–voltage characteristics were achieved. Ultraviolet emission dominates in the electroluminescence spectra of the ZnO LED. An output power of 32 nW at an applied current of 60mA was demonstrated. The enhanced output power, as compared to those made on silicon substrates, is attributed to the improved ZnO film quality on sapphire substrates, which is confirmed by X-ray diffraction rocking curve studies. # 2010 The Japan Society of Applied Physics