Luminescence intensity and lifetime dependences on temperature for Nd-doped GaP and GaAs

We report the studies of luminescence intensity and lifetime dependences on temperature for Nd-doped GaP and GaAs samples grown by metalorganic chemical vapor deposition. It is found that, with above band-gap excitation, the temperature dependence of GaP:Nd reveals a two-step decreasing behavior as the sample temperature increases. This phenomenon is due to the fact that there exist two kinds of Nd centers (type I and type II) in GaP. Although type I Nd centers produce strong luminescence at low temperatures, their intensities drop rapidly above 40 K. On the other hand, type II Nd centers show a near constant intensity up to 150 K and can still be observed up to room temperature. We also found, for a given Nd center, that the luminescence lifetime dependence on temperature is identical to the temperature quenching behavior of luminescence intensity. From the similarity between the quenching behaviors of Nd-related luminescence intensities and lifetimes, we conclude that the temperature quenching of luminescence intensity of these Nd-doped GaP and GaAs samples is mainly due to deexcitation rather than the reduction of excitation efficiency.