Growth of III-nitride quantum structures for device applications

Using GSMBE with ammonia on (0001) sapphire substrates, AlN/AlGaN nanostructured short period superlattices (SPSLs), with respective well and barrier thickness from 0.5 to 1 nm and from 0.75 to 1.5 nm, have been shown to have energy gaps in the deep UV suitable for light emitting diodes (LEDs) and photodetectors (PDs) operating down to 247 nm. Performance of LEDs and PDs is limited by factors including efficiency of radiative recombination and absorption in the active region and electrical resistivity of p-type wide bandgap SPSLs. Based on MOVPE, we have used selective area epitixy (SAE) to grow InGaN/GaN quantum structures. By patterning SiO₂ hard mask materials on planar sapphire substrates, we have grown various shapes including pyramidal stripes with InxGa_1-xN multiple quantum wells. The structures at the apex are found to have very high In content with corresponding optical emission in the green wavelength range and excellent uniformity.