InAlN layers grown lattice-matched to GaN have been used to optimize the internal quantum efficiency of InGaN quantum-well device structures emitting in the green region of the visible spectrum. The electron-blocking properties of InAlN layers significantly depend on their growth temperature. Devices with InAlN layers grown at 780 and 840 °C exhibit significant variations in the quantum well emission characteristics, with 780 °C producing the highest emission efficiency. Three- and two-dimensional growth modes are observed in the layers grown at low and high temperatures, respectively. The former should allow higher hole transport through the narrow regions of the blocking layer. © 2010 The Japan Society of Applied Physics.