A novel epitaxial lift-off process for III-nitrides, involving selective removal of a sacrificial (Al, In)N layer in a hot nitric acid etchant, is reported. This was applied to the fabrication of 1 - lambda GaN planar microcavities bounded by two dielectric DBRs, starting from epitaxial GaN-(Al, In)N-GaN trilayers grown on free-standing GaN or high-quality GaN template material. An optically smooth surface was retained on the GaN (000 (1) over bar) surface exposed to the nitric acid etch, with root mean square roughness values as low as 2 nm over 8 mu m x 8 mu m areas. Photoluminescence and reflectivity spectra were recorded from completed microcavities, and the latter showed clear dips in the region of 3.5 eV. (C) 2009 Elsevier Ltd. All rights reserved.