Tuning the electrical properties of ZnO-Si nano-contacts and its effect on field electron emission from ZnO nanowires

ZnO nanowire (NW) is one of the promising cathode materials for vacuum micro/nano electronic devices. Optimization on its field emission performance is one of the important issues. In present study we explored the effect of ZnO-Si (n⁺⁺ doped) nanojunctions electrical properties on field emission. Arrays of individual ZnO NWs on Si nanorods were fabricated. The electrical and field emission measurements were in-situ performed using nano-manipulated probes. The ZnO-Si n-n junction showed a lower junction barrier of 0.3~0.6 eV, with good uniformity of 50% in electrical properties. Moreover, by applying strain on the Si nanorod to narrow its band gap, the effective contact resistance of the ZnO-Si nanojunction was dramatically decreased up to 10 times at a strain of 10%. The junction barrier was decreased to ~0.1 eV, showing significant enhancement on field electron emission. This work directly demonstrated that (i) the effect of electrical nano-contact is of great important for vacuum nanoelectronic devices; (ii) heavily n-type doped semiconductor with narrower band is promising be used as cathode electrode.