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-phase 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 unity. The dislocation density tends to rose when the flow ratio increases, and carriers of the film accumulate 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 & Technology B, 2006, 24[1], 108-12