High-quality and highly-transparent AlN template on annealed sputter-deposited AlN buffer layer for deep ultra-violet light-emitting diodes

Abstract

A high-quality and highly-transparent AlN template was prepared by regrowth on a sputter-deposited AlN buffer layer. The buffer layer was thermally annealed and then underwent AlN regrowth in metalorganic chemical vapor deposition (MOCVD). The peakwidth of (002) and (102) plane x-ray rocking curve was 104 arcsec and 290 arcsec, respectively, indicating a threading dislocation density <5.0 × 108 cm−2. Dislocations were reduced via grain growth and morphological evolution. The absence of carbon impurity source in sputter deposition also resulted in an improved transparency. According to transmission and reflection measurements, the absorption rate of λ=280 nm emission propagating through the template was less than 6%.