THREADING DISLOCATIONS IN IN-DOPED GAAS SI

The threading dislocation morphologies and characteristics in In-doped 3-mu-m-thick GaAs films grown by molecular-beam epitaxy on Si (100) substrates tilted toward the [110] orientation by 2-degrees have been examined mainly using cross-sectional transmission electron microscopy. Most of the observed threading dislocations are 30-degrees- and 60-degrees-type dislocations along the <211> and <110> directions on inclined {111} planes. Also, screw-type dislocations running parallel to the [001] growth direction are frequently detected. No appreciable effect of homogeneous In doping throughout the films with a content between 2 x 10(19) and 2 x 10(20) atoms/cm3 on the reduction of threading dislocation generation is observed. However, an In content of 2 x 10(20)/cm3 (a misfit of 7.5 x 10(-4)) in GaAs films doped in the middle of growth is found to be effective for changing the dislocation direction on the {111} planes.