November 4, 2004 – Scientists from Royal Philips Electronics and the Kavli Institute of Nanoscience at Delft U., The Netherlands, claim they’ve achieved the first successful integration of III-V nanowires on germanium and silicon substrates.
Growing a layer over the entire substrate via conventional thin-film deposition and lithography techniques creates lattice and thermal expansion mismatch, preventing epitaxial growth of crystallographic structures essential to material properties such as low interface resistance needed in transistors and LEDs, according to the researchers. So, rather than layering over the entire substrate and removing unneeded parts, the researchers grew indium phosphide nanowires in substrate locations where needed, resulting in many small individual structures, and easier relief of mechanical stress on the substrate.
Key to the process is a vapor-liquid-solid method. After gold seeds are deposited in the substrate using conventional lithography processes, the semiconductor material is applied to the substrate in vapor form, dissolving into the metal seed. The seed becomes oversaturated and grows the material in the form of nanowire starts.
Although Erik Bakkers, senior scientist at Philips Research, acknowledged the process is not new, he explained that this is the first time III-V material has been grown on both germanium and silicon substrates. The research was published in the Nov. 4 issue of the journal Nature Materials.