Non-polar (1 1 (2) over bar 0) a-plane GaN films have been grown by low-pressure metal-organic vapor deposition on r-plane (1 (1) over bar 0 2) sapphire substrate. We report on an approach of using AlN/AlGaN superlattices (SLs) for crystal quality improvement of a-plane GaN on r-plane sapphire. Using X-ray diffraction and atomic force microscopy measurements, we show that the insertion of AlN/AlGaN SLs improves crystal quality, reduces surface roughness effectively and eliminates triangular pits on the surface completely. (C) 2009 Elsevier B.V. All rights reserved.