The surface morphology and the room temperature 1.54 mu m photoluminescence (PL) intensity have been investigated as a function of Er flux in GaN:Er grown by merallorganic molecular beam epitaxy. Unlike AIN, GaN:Er showed improved surface smoothness as evidenced by atomic force microscopy and scanning electron microscopy, with root mean square roughness values improving from 18.1 to 2.0 nm as the Er cell temperatures were increased from 1250 to 1450 degrees C. Similarly the PL emission increased with increasing Er concentration and showed no evidence of saturation or concentration quenching.