In a recent study, researchers at Hokkaido University in Japan have proposed and demonstrated GaAs nanowire fabrication on poly-Si substrates using selective-area metal organic vapour-phase epitaxy (SA-MOVPE). The key to obtaining nanowires on poly-Si was the use of a SiO2 mask layer with nanometre-scale openings. Under the appropriate growth conditions of MOVPE, GaAs crystal growth occurs only at the mask opening, where the poly-Si surface is exposed. The crystal growth can proceed in a similar way to on a single crystal substrate, when the size of mask opening is equivalent to that of a grain of poly-Si.

Evaluation of the grown shapes and growth characteristics revealed that GaAs nanowires grown on poly-Si substrates have the same growth mechanism as conventional GaAs NWs grown on single-crystalline GaAs or Si substrates. Experiments showed that the wire structure yield can be improved by increasing the Si grain size and/or increasing the Si deposition temperature. The growth model proposed for understanding nanowire growth on poly-Si is based on the mask opening size, the Si grain size, and the growth conditions. The ability to control the growth mode is promising for the formation of nanowires with complex structures on poly-Si thin layers.

The next target of this study is the formation of nanowires with complex structures, such as core-shell heterostructures and pn junctions, on poly-Si thin layers, and the realization of cost-effective and resource-efficient nanowire LEDs.

Additional details can be found in the journal Nanotechnology.