Zero-dimensional field emitter based on ZnO quantum dots

ZnO quantum dots (QDs) with diameter around 6 nm were grown by a catalyst-free metalorganic chemical vapor deposition method and applied as electron field emitters. The Ga doping resulted in a considerable improvement of the field emission properties. Macroscopic field emission measurements revealed that the Ga-doped ZnO QDs have a low turn-on field of 1.3 V/mu m and a large field enhancement factor up to 10(4). Probe force microscopy and scanning field emission probe microscopy were used for mapping at submicrometer scale of the spatial distribution of the work function and the field emission, respectively. The local measurements indicated a spatial correlation between both properties that could be linked to spatial variations of the Ga doping level. c 2010 American Institute of Physics. [doi:10.1063/1.3496443]