Threading dislocations in In-doped GaAs/Si

The threading dislocation morphologies and characteristics in In-doped 3-μm-thick GaAs films grown by molecular-beam epitaxy on Si (100) substrates tilted toward the [110] orientation by 2° have been examined mainly using cross-sectional transmission electron microscopy. Most of the observed threading dislocations are 30°- and 60°-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 2×1019 and 2×1020 atoms/cm3 on the reduction of threading dislocation generation is observed. However, an In content of 2×1020/cm3 (a misfit of 7.5×10−4) in GaAs films doped in the middle of growth is found to be effective for changing the dislocation direction on the {111} planes.