Polycrystalline GaN for light emitter and field electron emitter applications

We have grown polycrystalline GaN on quartz, refractory metal (W, Mo, Ta and Nb) and Si substrates by using plasma-assisted molecular beam epitaxy. It has been found that polycrystalline GaN grown on quartz and refractory metal substrates shows a strong band-edge emission without yellow emission. GaN growth on Si with native oxide produces well c-orientated nanorods exhibiting a low field emission threshold and high emission current density. We will review the growth of polycrystalline GaN films and the evaluation of their optical properties and electron field emission characteristics.