InGaN/GaN nanowire green light emitting diodes on (001) Si substrates

Progress in solid state lighting at the present time primarily involves the research and development of visible nitridebased light emitting diodes (LEDs) and perhaps lasers in the future. However, this development has been impeded due to the lack of high-quality and low-cost GaN substrate. Successful growth of GaN and InGaN nanowires on silicon and other mismatched substrates has been demonstrated recently. The nanowires exhibit significantly reduced defect density due to their large surface-to-volume ratio. A reduced strain distribution in the nanostructures also leads to a weaker piezoelectric polarization field. Other advantages include large light extraction efficiency and the compatibility with lo w-cost, large area silicon substrates. In the present study, we have conducted a detailed investigation of the molecular beam epitaxial (MBE) growth and optical properties of (In)GaN nanowires directly on (001) Si in the absence of a foreign metal catalyst. Green LEDs have been fabricated with an ensemble of nanowires and the characteristics of these devices are also presented.