Epitactically interpenetrated high quality ZnO nanostructured junctions on microchips grown by the vapor-liquid-solid method

The usability of nanostructures in electrical devices such as gas sensors critically depends on the ability to form high quality contacts and junctions, at least in a two terminal setup. For the fabrication of various nanostructures, vapor-liquid-solid (VLS) growth is meanwhile a widely spread and very efficient technique for many semiconductors. However, as already demonstrated in the literature, forming contacts with the VLS grown structures to utilize them in a device is typically tedious. Either the substrate material has to be the same, such as the VLS material, or a laborious procedure has to be used to connect one side with the other. As a strikingly simple alternative approach, we report that the ability of VLS grown nanostructures to interpenetrate each other in a homoepitactical manner can be used to form a connecting bridge between two gold contact lines on a microchip. Other methods of direct growth are already established, but they lead only to a touching of the nanowires and not to interpenetration. The ZnO interpenetration junctions can be directly used as electrical devices, and just as a proof of principle, they were employed as UV-light dependent resistor, field effect transistor (FET), or gas sensor.