Growth and microstructure of InxGa1-xN films grown on SiC substrates via low pressure metalorganic vapor phase epitaxy

The growth and microstructures of InxGa1-xN films (x less than or equal to0 .23) grown on alpha (6H)-SiC(0001) wafer/AlN buffer layer/ GaN heterostruct ures by low pressure metalorganic vapor phase epitaxy have been investigate d. The system deposition pressure limited the InN content in these films. T he maximum InN contents achievable at the deposition pressures of 45 and 90 torr were similar to 13 and similar to 23%, respectively. Kinetic phenomen a based on the rates of adsorption and desorption of the In growth species off the growth surface are presented to explain the film composition depend ence on the system pressure. The surface morphologies and microstructures o f the InxGa1-xN films were analyzed using several techniques, and the forma tion of pinhole defects in the films was investigated. Most of the pinhole defects were associated with threading dislocations with a c-component Burg ers vector. Edge-type dislocations were never observed to terminate in pinh oles in the samples observed here. Indium segregation to areas around the d efect areas was observed, as was an In compositional gradient in the growth direction. Based on experimental observations, the strain field around dis locations with a c-component Burgers vector could result in the increase of In atoms at the dislocation sites in the film, which result in a change to the local growth mode of the film and causes the pinhole defects to form. (C) 2000 Elsevier Science Ltd. All rights reserved.