InGaN quantum wells, with luminescence in the yellow region of the visible spectrum, have been studied using conventional and time-resolved cathodoluminescence. We observe the absence of strong localization effects and a relatively high internal quantum efficiency of ∼12%, which are unexpected for InGaN in this-long wavelength emission range. We have also observed a steady decrease of the peak emission energy, and a continuous increase in the radiative recombination lifetime with temperature up to 100 K. These two features are manifestations of recombination due to nonlocalized excitons. Nonradiative recombination centers, with activation energy of ∼6meV, appear to constitute the main mechanism limiting the internal quantum efficiency of these films. © 2010 American Institute of Physics.