Following the commercial availability of high power III-nitride light emitting diodes in the 370-540 nm range, a strong desire for efficient rare earth-doped (In)GaN epilayers has developed to produce light source and electrically pumped optical amplifiers in the visible and IR spectral region. To this end, Er-doped GaN epilayers have been grown by OVMPE with excellent crystal quality . Similar success has been achieved with in-situ doped Nd:GaN samples grown by plasma-assisted MBE . For each dopant, we have studied site-selective emission spectroscopy using combined excitation-emission spectroscopy (CEES) to give important insight for the optimization of the growth conditions. Aside from application in novel light sources, there has been an increasing interest in the magnetic properties of the dilute RE-dopants, which are found to introduce ferromagnetism to the GaN host  enabling the realization of spin-memory based on this class of material .