We report on a systematic study of In0.5Ga0.5As quantum dots Grown by the migration enhanced epitaxy technique. A maximum room-temperature luminescence wavelength of 1.37 mu m has been achieved. We observe the presence of two emission maxima, which we attribute to the formation and interaction of two different dot-size distributions. Photoluminescence data analysis shows the formation of large quantum dots with good size uniformity that emit at 1.3 mu m and longer due to the enhanced atomic migration lengths.