Sep 10, 2009
Non-tapered InN nanowires exhibit record narrow linewidths
The energy bandgap of InN has been a subject of debate for quite some time. The development of InN nanowires has also added more heat to this topic, largely due to the structures' tapered morphology and their resulting poor electrical and optical properties.
Recently, researchers at McGill University have come up with a way of making non-tapered, nearly homogeneous, and electronically pure InN nanowires on Si using molecular beam epitaxy. While conventional InN nanowires have been grown by introducing indium and nitrogen species to the substrate surface simultaneously, this latest approach involves the deposition of a thin indium layer prior to growth initiation, which can act as a seed to promote the nucleation and formation of InN nanowires. The presence of well-defined nucleation centres, in conjunction with optimized growth parameters, enables the formation of non-tapered InN nanowires directly on Si substrates.
The resulting InN nanowires exhibit excellent optical properties. Their photoluminescence linewidths are nearly a factor of 5–10 times smaller than those of conventionally grown InN nanowires. A measure of the photoluminescence emission spectra at various temperatures also reveals that their peak positions closely follow Varshni's equation in the temperature range 5–300 K – a first observation for InN.
Such high-quality InN nanowires will allow many fundamental properties of InN to be investigated in detail as never before. The structures will also emerge as a promising candidate for a new generation of solar cells, nanoscale lasers, high speed transistors and chemical and biological sensors.
The researchers presented their work in Nanotechnology.
About the authors
Yi-Lu Chang and Feng Li are PhD students in the Department of Electrical and Computer Engineering at McGill University. Zetian Mi is an assistant professor and the Hydro-Quebec Nano-Engineering Scholar in the Department of Electrical and Computer Engineering at McGill University.