Guided nanowires on scratched amorphous substrates

Epitaxial and graphoepitaxial relations between a semiconductor nanowire (NW) and a crystalline surface have been previously proven as a successful mean to fabricate various types of devices without the need of post-growth assembly. However, the guided growth approach is in dearth for a fast, large scale process when considering amorphous substrates. In this work we demonstrate the guided growth of four semiconductor materials (CdS, CdSe, ZnSe and ZnO) directly on the amorphous thermal oxide layer of a Si/SiO₂ substrate (SiO₂ layer is 300 nm thick) using a fast, non-lithographic process. A few seconds polishing with micron-sized diamonds creates nanoscale trenches on the amorphous layer, followed by deposition of catalyst and CVD synthesis in which the NWs grow inside and along the trenches in a vapor-liquid-solid (VLS) growth mechanism. This type of relations between the NW and the substrate is known as artificial epitaxy. The “on-chip” synthesis is further exploited to fabricate a field effect transistor (FET) device using CdS NWs while the SiO₂ layer serves as a back gate.
To show generality of this method, we also demonstrate guided growth of CdS NWs on scratched glass. We believe that this method is an effective way to integrate NWs directly on commonly used substrates thus advantageous for a wide range of industrial applications from photodetectors and photovoltaic cells to smart windows.