Abstract We have extended the spectral range of the current PL-upconversion apparatus to be operated in infrared. Using the IRPL-upconversion¡Awe study the behavior of carrier cooling of InN film and the relationship between the spacer and lifetime in InAs/GaAs stacked QDs . We excited InN film of the band gap of 0.74eV with ultrafast Ti:sapphire laser of the wavelength 404nm. We found the phonon emission time by hot carriers of InN is 14fs. The hot carriers release their excess energy to the lattice of 35K with a timescale of 100ps. We observed in InAs/GaAs QDs that the shorter life time for samples with thin spacer is due to tunneling effect.