Conducting atomic force microscopy and scanning surface-potential microscopy were applied to image the surfaces of Mg–In-co-doped GaN films grown by low-pressure metal-organic chemical-vapor deposition. Biscyclopentadienylmagnesium (CP2Mg) and trimethylindium (TMIn) were used as the co-doping sources in the experiment. The dislocation density at the film surface reduces to the lowest level (~1.0 x 109/cm2) when the TMIn/CP2Mg flow rate ratio was about 1. The dislocation density tends to rise when the flow ratio increased, and carriers of the film accumulated near the rim of the dislocation at an accelerated speed. The work function of dislocation was also found lower than that of non-dislocation areas. Such electrical unevenness may seriously influence the light emission of the component, which should not be ignored during fabrication and deserves careful attention.

Advanced Electrical Imaging of Dislocations in Mg–In Co-Doped GaN Films. S.H.Chen, S.P.Hou, J.H.Hsieh, F.C.Chang, W.K.Chen: Journal of Vacuum Science and Technology B, 2006, 24[1], 108-12