Experimental and theoretical results on extended defects in hexagonal GaN grown by metal organic vapour deposition were presented. Transmission electron microscopy measurements indicated the presence of 3nm-wide type I1 stacking faults related to the metal organic vapour deposition growth, and 2-4 nm stacking faults of unidentified type related to the ion implantation. Infinite stacking faults of various types, I1, I2 and I3, were simulated. First-principles calculations were used to model Shockley partial dislocations, the core structure of the dislocations and intrinsic stacking faults. Defect-level positions and the formation energy of the infinite stacking faults were estimated. Also presented were the results of calculations and available experimental data on finite-size stacking faults bounded by partial dislocations in wurtzite GaN. Calculation of the infinite stacking faults revealed shallow levels, but no deep levels. In the stacking faults bound by dislocations there were deep filled levels in the range of 0.4 to 0.8eV from the valence band maximum located at the atoms of the 90° dislocations. Also calculated was the segregation of the C, n-dopant, Si or O and the p-dopant, Mg, to the dislocations and stacking faults. The effect of the segregation was found to be stronger for stacking faults with partials. The results of the calculations were correlated with the experimental data on GaN obtained from high resolution transmission electron microscopic and Hall measurements. Mechanisms were suggested for the formation of the stacking faults I1 and I2 after ion implantation and high temperature annealed and the difficulties of p-type doping with formation of extended defects were explained.

Dislocations and Stacking Faults in Hexagonal GaN. I.G.Batyrev, W.L.Sarney, T.S.Zheleva, C.Nguyen, B.M.Rice, K.A.Jones: Physica Status Solidi A, 2011, 208[7], 1566-8