Realization of vertically well-aligned ZnO:Ga nanorods by magnetron sputtering and their field emission behavior

report catalyst-free growth of one-dimensional Ga-doped ZnO nanorod arrays on (001) Si substrate with a thin buffer layer by magnetron sputtering. The diameter and length of the nanorods are in the range of 90-144 nm and about 1.38 mu m, with an aspect ratio nearly 12:1 and deviation angle +/- 6 degrees between the [0001](ZnO) direction and substrate normal. The photoluminescence spectra of the nanorods are dominated by intense near band-edge emission with weak deep-level emission. The good field emission properties of the nanorod arrays with turn-on field of 2.9 V/mu m and enhancement factor of 2027 demonstrate the perfect single-crystalline growth of ZnO:Ga nanorods with similar vertical alignment.