In this work, we present a structure design L3 cavities of 2D photonic crystal on a triangular photonic crystal lattice on Gallium Nitride (GaN) with two different substrate sapphire and SiC. The designed was simulated with LUMERICAL finite different time domain (FDTD). The resonant wavelength and quality factor (Q-factor) of design PhC structure were studied. The forbidden region or stop band observed are between 420 to 520 nm. The performance of the Q-factor has been enhanced with sapphire and SiC substrate, where the highest Q-factor that obtained are 22 500 and 28 400 respectively.
