Scanning tunneling microscopy and spectroscopy of the electronic structure of dislocations in GaN/Si(111) grown by molecular-beam epitaxy

By using cross-sectional scanning tunneling microscopy, a correlation between the surface morphology and the corresponding electronic states of the dislocations terminated at the GaN (1̄100) cleavage surfaces grown by molecular-beam epitaxy has been demonstrated. Both scanning tunneling spectroscopy and analysis of the dislocations on electronic structures suggest that regions surrounding dislocations register gap states in the fundamental band gap of GaN. Closely examining the recognition of the electronic structure reveals that the defect levels could provide the possibility of yellow luminescence, involving a transition from the conduction-band edge to a level at 1.2 eV above the valence band edge.