ZnO:Ga nanowires with low turn-on field for field-emission lighting

ZnO:Ga nanowires were synthesized using a ZnO seed layer as a pseudo-catalyst by a vapor-phase transport method. Nanowire growth was facilitated along the longitudinal axis, and the aspect ratio was increased from 27.3 to 54.1 by doping with Ga3+, which also slightly enhanced growths of the (1 0 0) and (1 0 1) planes. The luminescent spectrum was narrower, more red-shifted, and less intense when the Ga3+ doping concentration was increased. However, the substitution of Ga for Zn enhanced the tunneling capability of electrons at the ZnO-vacuum interface. ZnO:Ga nanowires doped with 0.5 mol% of Ga3+ achieved a low turn-on electric field of 0.57 V/μm. A stable emission current of 0.85 mA/cm2 with fluctuations within ±12.9% was observed over 5 h of operation.