Growth of thick (112¯0) GaN using a metal interlayer

Abstract

Thick films of (112¯0)-oriented GaN have been grown on Ti-coated metal organic chemical vapor deposition templates using hydride vapor phase epitaxy. Significant reductions in crack density were observed enabling 240μm thick films to be grown on sapphire. The use of Ti interlayers was shown to generate significant fractions of voids at the interlayer regrowth interface facilitating void-assisted separation on cooling. Ti metal layers annealed under optimal conditions were found to produce a TiN nanomask suitable for lateral overgrowth during HVPE. An estimate of the void size required to allow spontaneous delamination of the substrate at the TiN–GaN interface is discussed with reference to growth conditions.

Defect reduction in (112̄0) nonpolar a-plane GaN grown on r-plane sapphire using TiN interlayers

“…We observed the minimum XRC FWHMs at 10 nm TiN interlayer, where the on-axis values were 432 arcsec and 497 arcsec along c-axis and m-axis, respectively. The results are much better than that with the traditional ELOG method, even the combination of ELOG and flow modulation epitaxial technique [7,15,16]. Before 10 nm TiN, the FWHM decreases with increasing TiN thickness, which indicates that the TiN interlayer has a significant effect on decreasing dislocation in the a-plane GaN.…”

Gallium nitride (GaN) on sapphire substrates for visible LEDs

“…The higher density of crystalline defects in a fi lm grown on a non-polar surface compared to a polar surface is due to the anisotropic in-plane strain in the fi lms . LEO (Haskell et al , 2003b), the insertion of a metal interlayer (Tavernier et al , 2004), sidewall epitaxial overgrowth (Imer et al , 2006), in situ SiN nanomasks (Chakraborty et al , 2006) and two-stage epitaxial lateral overgrowth (Ni et al , 2006) have been employed to reduce the density of crystalline defects.…”

Effect of InGaN/GaN Superlattice on Lattice Curvature of GaN Layers Grown on Sapphire Substrates

“…Therefore, the fabricated GaN substrate should have a small lattice curvature. To this end, GaN‐based interlayers, AlN‐related interlayers, TiN interlayers, and CrN interlayers have been introduced. In general, the bending of a freestanding GaN substrate is caused by the intrinsic stress originating from the defect density distribution along the growth direction.…”