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

Abstract

The introduction of Si burst during the growth of GaN film on Si(111) substrate by MOCVD formed a Six Ny 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 Ec–Et ∼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 Six Ny layer. Addition of TMAl burst for the AlN growth leads to a substantial reduction in trap concentration associated with the nitrogen vacancies, VN, and antisite of nitrogen, NAl, at Ec–Et ∼0.10 eV and Ec–Et ∼ 0.60 eV respectively. This improves the quality of the subsequent layer of HT‐GaN grown and is useful for device fabrication. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)