Defect evolution and accompanied change of electrical properties during the GaN growth by metalorganic chemical vapor deposition

The defect evolution and its correlation with electrical properties of GaN films grown by metalorganic chemical vapor deposition are investigated. It is found that the dislocation density decreases gradually during the growth process, and the dislocation reduction rate in the island coalescence process is especially rapid. The changes in electron mobility of GaN with the increase of growth time are mainly dependent on the dislocations acting as scattering centers. Furthermore, the variation of carrier concentration in GaN may be related with the point defects and their clusters. The quality of GaN could be improved by suitably increasing the film thickness.