The introduction of Si burst during the growth of GaN film on Si(111) substrate by metal organic chemical vapour deposition formed a SixNy layer which led to an effective reduction in the density of screw dislocations. The reduction was associated with bending of screw dislocations to form a square dislocation loop when neighbouring dislocations with opposite Burger's vector paired up. The concentration of electron traps Ec-Et ≈0.17-0.26eV which was associated with screw dislocations was substantially reduced and a kink was left at the silicon rich position. The mixed-edge dislocation, however, was not annihilated by the SixNy layer. Addition of TMAl burst for the AlN growth led to a substantial reduction in trap concentration associated with the N vacancies, VN, and antisite of nitrogen, NAl, at Ec-Et ≈0.10eV and Ec-Et ≈0.60eV respectively. This improved the quality of the subsequent layer of HT-GaN grown and was useful for device fabrication.

Deep Levels Associated with Dislocation Annihilation by Al Pre-Seeding and Silicon Delta Doping in GaN Grown on Si(111) Substrates. C.B.Soh, K.Y.Zang, L.S.Wang, S.Y.Chow, S.J.Chua: Physica Status Solidi A, 2008, 205[2], 266-70