Mg-alloyed ZnO nanocombs for self-gating photodetectors.

Mg-alloyed ZnO nanocombs were synthesized by the chemical vapor deposition method. The morphology and optoelectronic properties of the nanocombs were systematically investigated. The photodetection capability of the Mg-alloyed ZnO nanocomb was demonstrated by fabrication of a two terminal nanocomb device. It was found that the nanocomb with a high surface-to-volume ratio absorbed the photons effectively in the 310-400 nm range and enabled ultra-high photoconductive gain of 1.9 × 106. From experiments and theoretical analysis, the teeth part of the nanocomb served as a negative gate upon accumulation of electrons by adsorption of oxygen molecules at the teeth, which reduced the dark current of the backbone of the nanocomb and led to an increase in the photoconductive gain of the nanocomb detector.