Laterally over-grown epitaxial GaN on free-standing GaN was used to reduce the numbers of threading dislocations which were scattered over the surface. The threading dislocation density, in the GaN layer which was above the window area surrounding the SiO2 mask, was reduced to 5 x 107/cm2, and that in the GaN layer above the SiO2 mask area was reduced to 7 x 105/cm2.

High-Power and Long-Lifetime InGaN Multi Quantum-Well Laser Diodes Grown on Low Dislocation-Density GaN Substrates. S.Nagahama, N.Iwasa, M.Senoh, T.Matsushita, Y.Sugimoto, H.Kiyoku, T.Kozaki, M.Sano, H.Matsumura, H.Umemoto, K.Chocho, T.Mukai: Japanese Journal of Applied Physics - 2, 2000, 39[7A], L647-50