The authors demonstrate the fabrication of suspended photonic crystal membranes in GaN films deposited on Si(111). The photonic crystal patterns fabricated in these membranes consisted of triangular arrays of holes having diameters in the range of 70-175 nm, with a lattice spacing of 200-500 nm. The patterns included optical cavity structures (groups of missing holes), which are predicted to exhibit resonances in the visible to near-IR spectral region. Such suspended photonic crystal membranes may serve as the basis for efficient wavelength-scale GaN-based light emitters monolithically integrated with Si. (c) 2007 American Vacuum Society.