Hexagonal lattice photonic crystal microcavities with modified single missing air-hole defects were fabricated in suspended InAs/InP quantum dot membranes. The cavity modes predicted from finite-difference time-domain simulations are observed in photoluminescence measurements. The resonant energies of the defect modes are tuned across the band gap of the photonic crystal through modifications of the size and position of the inner ring holes surrounding the defect. Up to a 20-fold enhancement of the quality factor of the modes are observed as they are tuned across the band gap, with measured Q values of up to 6000. (c) 2006 American Vacuum Society.