We present techniques for fabricating photonic crystal (PC) membrane defect lasers. These nanostructures operate as optically pumped lasers under pulsed conditions at room temperature. The thin inembrane PC defect structures are formed by transferring an electron-beam lithographically defined lattice pattern into an epitaxial layer Structure by a sequential process of ion beam etching, reactive ion etching, and electron cyclotron resonance etching steps. A V-shape undercut channel is formed by a wet chemical etching using a 4:1 mixture of HCl and H,O-2 to create the suspended membrane. We include a detailed description of a dependable and repeatable HCl undercut process for the PC structure.