The effect of dislocations upon the electrical characteristics of p-n junctions was studied by means of current-voltage measurements. Lateral epitaxial overgrowth was used to produce areas of low dislocation density which were close to areas having the high dislocation density which was typical of growth on sapphire. A comparison of diodes fabricated in each region revealed that reverse-bias leakage currents were reduced by 3 orders of magnitude on lateral epitaxially overgrown GaN. Temperature-dependent measurements indicated that the remaining leakage current in devices was associated with a deep trap level.

P.Kozodoy, J.P.Ibbetson, H.Marchand, P.T.Fini, S.Keller, J.S.Speck, S.P.DenBaars, U.K.Mishra: Applied Physics Letters, 1998, 73[7], 975-7