An etching technology for the patterning of suspended GaN structures on lattice matched AlInN sacrificial layers is studied. Selective dry RIE etching of GaN to AlInN is demonstrated, which allows effective pattern transfer without affecting lower layers. On the other hand, wet etching of AlInN in highly concentrated KOH solutions has also been studied. We show that high vertical and lateral etch rates are possible. For a fast and selective etching suitable for MEMS technology, a high density of defects at the surface is required due to their positive influence on the lateral etch rate. (c) 2007 Elsevier B.V. All rights reserved.