Ultrafast hot carrier dynamics in InN epitaxial films

Ultrafast hot carrier dynamics in Indium nitride (InN) epitaxial films were investigated by femtosecond time-resolved pump-probe reflection measurements. Carrier density and carrier energy dependence of the hot carrier dynamics in InN were studied by varying the pump laser power and wavelength, respectively. Experimental results showed that the hot carrier relaxation can be fitted by a biexponential relaxation process. The fast relaxation rate increased with increasing carrier density ( N ), which was measured as N 0.5 . The fast relaxation rate also increased with increasing carrier energy ( E ), which was measured as E 0.53 . These observations revealed that electron-electron scattering plays an important role in the fast relaxation process. The slow relaxation process was found to be dominated by Auger scattering and the slow relaxation rate was independent of the carrier energy. The defect-related trapping time in InN was estimated to be ~515 ps.