DIFFUSE-X-RAY SCATTERING FROM MISFIT DISLOCATIONS AT SEMICONDUCTOR HETEROINTERFACES

X-ray diffuse scattering in (001) InGaAs/(AlGa)As transistor structure s of high electron mobility was observed for structures whose InGaAs c hannel thickness substantially exceeded the critical thickness for mis fit dislocation formation. The diffuse scattering was determined to or iginate from misfit dislocations, as confirmed by plan-view transmissi on electron microscopy. Diffuse scattering was measured using triple-a xis x-ray diffraction, which showed that the diffuse scattering was se nsitive to the density and direction of the misfit dislocations. Using transmission electron microscopy for calibration, we determined that the diffuse scattered intensity was directly proportional to the dislo cation density. For samples with misfit dislocations along only [(1) o ver bar 10], diffuse scattering was confined to a crystallographic dir ection that was perpendicular to the misfit segments, but for samples with thicker InGaAs layers (and with misfit segments in both [110] dir ections) diffuse scattering extended along all azimuthal directions. W e also determined that observation of directional diffuse scattering p rovided a more sensitive means of detecting misfit segments than other commonly used techniques.