Electroluminescence from n-ZnO nanowires/p-GaN heterostructure light-emitting diodes

Abstract

The investigation explores the fabrication and characteristics of ZnO nanowire (NW)/p-GaN/ZnO NW heterojunction light-emitting diodes (LEDs). Vertically aligned ZnO NWs arrays were grown on the p-GaN substrate. The n-p-n heterojunction LED was fabricated by combining indium tin oxide/glass substrate with the prepared ZnO NWs/p-GaN substrate. The symmetrical rectifying behavior demonstrates that the heterostructure herein was formed with two p-n junction diodes and connected back to back. The room-temperature electroluminescent emission peak at 415 nm was attributed to the band offset at the interface between n-ZnO and p-GaN and defect-related emission from ZnO and GaN. Finally, the photograph indicated the LED clearly emitted blue light.

ZnO nanorod/GaN light-emitting diodes: The origin of yellow and violet emission bands under reverse and forward bias

“…6 Under reverse bias, large current has been observed. n-ZnO/p-GaN heterojunction devices without intrinsic or insulating layers frequently show leaky I-V curves 6,9,10,14,17,29 in agreement with large currents under reverse bias observed in our work. Large leakage current was previously attributed to Pool-Frenkel effect.…”

“…2 and 3) and interfacial recombinations, 2 recombination on defects in p-GaN, 17 shift due to the energy band offsets in n-GaN/pZnO heterojunction, 23 as well as the presence of interfacial layer resulting in charge accumulation and bandgap renormalization. 27 Similar to yellow-orange emission, from the presence of this emission in the absence of ZnO, violet emission likely originates from p-GaN structures.…”

One-dimensional ZnO nanostructures: Solution growth and functional properties

“…In addition, it has been suggested that the ZnO nanowire/GaN substrate heterojunction has a higher carrier injection efficiency and a higher recombination rate than other junctions [370].…”

“…Ohmic contacts to the bottom p-GaN and top n-ZnO nanowires were made by Ni/Au and ITO films, respectively. The need for deposition of an ohmic electrode on the GaN substrate could be avoided by employing a ZnO nanowire/GaN substrate/ZnO nanowire heterostructure [370]. The turn-on voltage of the diode was about 3.5 V, which is relatively low, probably due to the presence of interfacial defects [372] owing to the low growth temperature (< 100 °C ) of the chemical method.…”

Zinc Oxide Nanophotonics

“…The round-shaped spot is originated from the whole disk-shaped ZnO nanowires layer. Most previous works exhibited a strong EL emission from forward bias beyond 10 V at higher wavelength [148][149][150][151][152]. Another study showed different EL behavior from other nZnO/p-GaN heterojunctions where the EL generated only from either the n-ZnO or p-GaN side [143].…”