Ultraviolet electroluminescence from ZnO-based light-emitting diode with p-ZnO:N/n-GaN:Si heterojunction structure

A p-ZnO:N/n-GaN:Si structure heterojunction light-emitting diode (LED) is fabricated on c-plane sapphire by full metal organic chemical vapor deposition (MOCVD) technique. The p-type layer with hole concentration of 8.94 x 10(16) cm(-3) is composed of nitrogen-doped ZnO using NH(3) as the doping source with subsequent annealing in N(2)O plasma ambient. Silicon-doped GaN film with electron concentration of 1.15 x 10(18) cm(-3) is used as the n-type layer. Desirable rectifying behavior is observed from the current-voltage (I-V) curve of the device. The forward turn on voltage is about 4 V and the reverse breakdown voltage is more than 7 V. A distinct ultraviolet (UV) electroluminescence (EL) with a dominant emission peak centered at 390 nm is detected at room temperature from the heterojunction structure under forward bias conditions. The origins of the EL emissions are discussed in comparison with the photoluminescence (PL) spectra. (C) 2010 Elsevier B.V. All rights reserved.