Fully-relaxed n-AlGaN on AlN / Al2O3 templates using strain-relaxed super-lattice buffer layers

Strain relaxation, surface morphology, and threading dislocations of 2.5–μm-thick n –Al 0.6 Ga 0.4 N, grown by metal–organic chemical vapor deposition on AlN/Al 2 O 3 templates using strain relaxed super lattice (SRSL) buffer layers, are investigated. The SRSLs are consisted of 11–115 nm Al 0.50 Ga 0.50 N/23 nm Al 0.75 Ga 0.25 N multiple layers. The n –Al 0.6 Ga 0.4 N layer is fully strain relaxed and smooth surface morphology when grown on the SRSL with Al 0.50 Ga 0.50 N thickness over 69 nm. The full width at half maximum values of X–ray rocking curves of n -Al 0.6 Ga 0.4 N for ( 0002 ) and ( 10 1 ‾ 2 ) planes are 237 and 468 arcsec, respectively. The threading screw dislocations and threading edge dislocations are estimated as 1.2 × 10 8 cm −2 and 1.1 × 10 9 cm −2 , respectively. The SRSL buffer layer enables to achieve 100% strain relaxation together with a smooth surface and a low threading dislocation density. • Al 0.50 Ga 0.50 N/Al 0.85 Ga 0.15 N strain–relaxed super lattice (SRSL) buffer layer is applied for UV –light emitting devices. • MOCVD – grown n-Al 0.6 Ga 0.4 N/SRSL/AlN/Al 2 O 3 is investigated by AFM and XRD. • The n-Al 0.6 Ga 0.4 N layer is fully strain relaxed and smooth surface when grown on a relatively thick SRSL buffer layer. • TSDs and TEDs are estimated as 1.2 × 10 8 cm −2 and 1.1 × 10 9 cm −2 , respectively.