Two-dimensional photonic crystal defect lasers in InGaAsP membranes directly bonded to a SiO(2)/Si substrate have been demonstrated. Lasing at wavelengths near 1550 nm was obtained with incident threshold pump powers as low as 1.5 mW. Good agreement between experimental data and three-dimensional finite-difference time-domain (FDTD) simulation was achieved. The thermal impedance of this laser is also characterized.