Drastic improvements of GaN film quality by applying Si irradiation during growth interruption in rf-MBE

Si irradiation during growth interruption is applied to GaN growth in radio-frequency molecular beam epitaxy. It is found that the surface morphology of GaN is greatly improved. Atomic force microscopy observation illustrates that a flat surface with clear monolayer steps can be achieved without using metalorganic chemical vapor deposition-grown GaN templates. Furthermore, highresolution X-ray diffraction (XRD) measurements of the Si-irradiated GaN sample show that the FWHM value of the (002) diffraction peak is less than 100 arcsec and that of the (102) diffraction peak is as narrow as 550 arcsec. The XRD results imply that the dislocation density in the Si-irradiated sample is greatly reduced, which is confirmed by cross-sectional scanning tunneling electron microscopy observations.