Trap level characteristics of rare-earth luminescence centers in III–V semiconductors

We have applied a multiphonon-assisted energy transfer model, which has been verified for the Yb-doped InP system, to Er-doped GaAs, Nd-doped GaP, and Nd-doped GaAs. By applying this model, the temperature dependence of the decay time of the 4f-shell luminescence can be calculated using two parameters. One parameter is the energy transfer probability between the rare-earth 4f shell and the semiconductor host, and the other is the energy which has to be compensated for in the energy transfer processes. The values of these two parameters were determined by fitting the calculated temperature dependence to the experimentally obtained results. The calculated temperature dependences fit with the experimental results well, showing that the energy transfer mechanism in these materials is similar to that in InP:Yb. The estimated values of energy which have to be compensated for enable us to estimate the energy level positions responsible for the rare-earth intra-4f-shell luminescence. The values of the transition matrix elements obtained by the fitting were rather large, suggesting that the energy transfer between the rare-earth 4f shell and the semiconductor host is efficient in spite of the fact that it is a phonon-assisted process.