Reducing the warpage and dislocation density of GaN template grown by HVPE with gallium droplet treatment

Abstract

AbstractThe warpage of the GaN template grown by a HVPE with gallium droplet treatment (GDT) was 13.8 μm, which was reduced by 80.3% of the warpage for GaN template grown by conventional MOCVD and 43% of the warpage for GaN template grown by HVPE without GDT. The treatment of gallium droplets on sapphire was achieved by thermal evaporator at room temperature. The E2 high peak of GaN template with GDT showed at 566.5 cm‐1, whereas the E2 high peak of GaN template by MOCVD positioned at 569.5 cm‐1 in Raman scattering spectra. According to the frequency shifts of E2 high peak position for each template around 3 cm‐1, the release of compressive stress of GaN template grown by HVPE with GDT was shown. In study of FE‐SEM and Grow discharge spectroscopy (GDS), voids and concentration decline zones of gallium and aluminium in counter direction were formed at the interface between GaN epilayer and sapphire substrate during GaN growth by HVPE. We expected that the decrease of warpage and stress for GaN template with GDT could be caused by the formation of voids and concentration decline zones of gallium and aluminium. Etch pits density of GaN template with GDT was around 8.5x107/cm2. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)