AVS 53rd International Symposium
    Electronic Materials and Processing Thursday Sessions
       Session EM-ThP

Paper EM-ThP6
Electroluminescence from ZnO Nanowire/Polymer Composite p-n Junction

Thursday, November 16, 2006, 5:30 pm, Room 3rd Floor Lobby

Session: Electronic Materials and Processing Poster Session
Presenter: C.-Y. Chang, National Central University, Taiwan
Authors: C.-Y. Chang, National Central University, Taiwan
F.-C. Tsao, National Central University, Taiwan
C.-J. Pan, National Central University, Taiwan
G.-C. Chi, National Central University, Taiwan
H.T. Wang, University of Florida
J.-J. Chen, University of Florida
F. Ren, University of Florida
D.P. Norton, University of Florida
S.J. Pearton, University of Florida
K.-H. Chen, National Taiwan University, Taiwan
L.-C. Chen, National Taiwan University, Taiwan
Correspondent: Click to Email
Zinc oxide (ZnO) is an attractive candidate for UV light emission since it is an environmentally friendly material which be grown at low temperatures on cheap transparent substrates and has both a direct wide band gap of 3.3 eV and a very large exciton binding energy of 60meV,important for robust light emission. In addition, it has been suggested that semiconducting nanowires may offer additional advantages for light emission due to the increased junction area, reduced temperature sensitivity, enhanced polarization dependence of reflectivity and improved carrier confinement in 1-D nanostructures. The characteristics of a hybrid p-n junction consisting of the hole-conducting polymer poly(3,4-ethylene-dioxythiophene)-poly(styrene-sulfonate)(PEDOT/PSS) and n-ZnO nanorods grown on a n-GaN layer on sapphire are reported. To fabricate the nanowire light emitting devices, the nanowire array was first coated with polystyrene, followed by photoresist. Spin-coating of polystyrene was used to electrically isolate neighboring nanorods and a top layer of transparent conducting indium-tin-oxide (ITO) was used to contact the PEDOT/ PSS. Multiple peaks are observed in the electroluminescence spectrum from the structure under forward bias, including ZnO bandedge emission at ~383 nm as well as peaks at 430,640 and 748 nm. The threshold bias for UV light emission was <3 V, corresponding to a current density of 6.08 A.cm-2 through the PEDOT/ PSS at 3 V. These initial results show that a low-cost, low temperature process holds strong potential for ZnO-based UV light emission and reduces the requirement for achieving robust p-doping of ZnO films or substrates.