T. Maruyama et al., Emission quantum efficiency of undoped and Eu doped GaN determined by photocalorimetric spectroscopy, PHYS ST S-B, 216(1), 1999, pp. 629-632
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.