Photoelectrochemical properties of single crystalline and polycrystalline GaN grown by the Na-flux method

A single crystal and polycrystals of GaN grown by the Na-flux method were photoelectrochemically characterized. The flatband potential of the GaN single crystal was approximately 0.2 V anodic of the potential of the GaN layer grown by metal-organic vapor phase epitaxy. Clear photo-electrochemical response was observed for the GaN single crystal The turn-on slopes of the photocurrent for the poly-crystalline samples were gentler than the slope for the single crystaL The turn-on slopes were probably affected by the high resistivity of grain boundaries in the polycrystalline samples.