MOVPE growth and cathodoluminescence properties of GAN microcrystal co-doped with Zn and Si

A (1 1 1) Si micro-facet was fabricated by KOH anisotropic etching on a (0 0 1) Si substrate. On the (1 1 1) Si facet, a GaN:Zn, Si-microcrystal was grown by selective metal-organic vapor phase epitaxy using an AlN intermediate layer and covered with an AlN capping layer. The size of the AlN/GaN/AlN microcrystal was determined by that of the (1 1 1) Si facet on the substrate. The optical properties of sample were evaluated by cathodoluminescence (CL) measurement. The CL intensity of DAP emission band was enhanced by reducing the crystal size. On the other hand, in the case of samples without AlN capping layer, the CL intensity was decreased with the smaller crystals. This result suggests that the optical confinement does enhance the CL intensity in the AlN/GaN/AlN sample.