The white LED development was made possible by systematic studies of the InGaN quantum well photoluminescence for growth on underlying GaN nanowire arrays with different diameters and densities. The InGaN emission appeared at longer wavelengths for larger wire diameters, a phenomenon attributed to diameter-dependent indium incorporation efficiency during growth.

"The key finding is that the GaN nanowire array geometry, in addition to the InGaN growth conditions, can be used to control the luminescence characteristics of the device."

The key finding is that the GaN nanowire array geometry, in addition to the InGaN growth conditions, can be used to control the luminescence characteristics of the device. It was also found that growth on low-density arrays with large spaces between the nanowires resulted in broad luminescence spectra comprised of two distinct bands of different colours. The latter effect is attributed to the deposition of InGaN layers of different compositions on the sidewalls and tops of the nanowires. The key finding is that the GaN nanowire array geometry, in addition to the InGaN growth conditions, can be used to control the luminescence characteristics of the device. Controlling both of these parameters makes it possible to tune the emission colour.

Future work includes transferring the growth technology from MBE to a MOCVD process suitable for production and improving the brightness and efficiency of the nanowire LEDs.

The researchers presented their work in the journal Nanotechnology.