Asymmetry of misfit-dislocation induced satellite peaks in semiconductor heterostructures

We examined GaAs/In0.05Ga0.95As/GaAs structures to quantify the relationshi p between misfit dislocation densities and the intensity of satellite peaks adjacent to the epitaxial layer Bragg reflections. Triple-axis x-ray diffr action rocking curves, double-axis x-ray topography and plan-view transmiss ion electron microscopy were employed to confirm other theoretical work, wh ich suggested that the diffuse scatter satellite peaks can be related to th e density of misfit dislocations. Symmetric (004) triple axis omega-scans a long the [110] direction showed an asymmetry in the satellite heights on ei ther side of the coherent peak which can be attributed to a difference in t he population of the misfit dislocation Burgers vectors. A (0.298 +/- 0.072 ) mu m(-1) tilt of the diffuse scattered contribution (which includes the l obes) accompanied the lobe height asymmetry. Measurements taken along the [110] direction showed a reduction of intensit y and more symmetric lobes. These results confirm that the lobes originate from misfit dislocations, that the difference in the lobe intensity provide s information about the Burgers vectors, and that the lobe periodicity orig inates from the layer thickness and not from the distance between the dislo cations. These results also indicate that triple axis rocking curve measure ments can provide an assessment of the distribution of misfit dislocation B urgers vectors in semiconductor heterostructures with low-dislocation densi ties.