Emission quantum efficiency of undoped and Eu doped GaN determined by photocalorimetric spectroscopy

The external emission quantum efficiencies were measured for undoped and Eu doped GaN by means of photocalorimetric spectroscopy (PCS). From the tempe rature dependence of the quantum efficiency, activation energies for therma l quenching of luminescence were evaluated for two undoped samples. It was found that the activation energies are almost the same at low temperature b etween two undoped samples, in spite of the difference in luminescence prop erty. This may be due to the difference in the density of the non-radiative recombination centers. We also measured PCS spectra for Eu doped GaN with red emission around 623 nm. PCS results show that the quantum efficiency of Eu doped GaN is extremely stable against temperature variation. The advant age of Eu doped GaN is shown to be a stable optoelectronic material against temperature variation.