Deep levels associated with dislocation annihilation by Al pre-seeding and silicon delta doping in GaN grown on Si(111) substrates

The introduction of Si burst during the growth of GaN film on Si(111) substrate by MOCVD formed a SixNy layer which leads to an effective reduction in the density of screw dislocations. The reduction is 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 E-c-E-t similar to 0.17-0.26 eV which is associated with screw dislocations is substantially reduced and a kink is left at the silicon rich position. The mixed-edge dislocation, however, is not annihilated by the SixNy layer. Addition of TMAl burst for the AN growth leads to a substantial reduction in trap concentration associated with the nitrogen vacancies, V-N, and antisite of nitrogen, N-Al, at E-c-E-t similar to 0.10 eV and E-c-E-t similar to 0.60 eV respectively. This improves the quality of the subsequent layer of HT-GaN grown and is useful for device fabrication. (C) 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.