The influence of He implantation and annealing on the relaxation of Si 0.7 Ge 0.3 layers on Si ͑100͒ substrates is investigated. Proper choice of the implantation energy results in a narrow defect band Ϸ100 nm underneath the substrate/epilayer interface. During annealing at 700-1000°C, He-filled bubbles are created, which act as sources for misfit dislocations. Efficient annihilation of the threading dislocations is theoretically predicted, if a certain He bubble density with respect to the buffer layer thickness is maintained. The variation of the implantation dose and the annealing conditions changes density and size of spherical He bubbles, resulting in characteristic differences of the dislocation structure. Si 1Ϫx Ge x layers with Ge fractions up to 30 at. % relax the initial strain by 70% at an implantation dose of 2ϫ10 16 cm Ϫ2 and an annealing temperature as low as 850°C. Simultaneously, a low threading dislocation density of 10 7 cm Ϫ2 is achieved. The strain relaxation mechanism in the presence of He filled bubbles is discussed.

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A newly developed laser powered heating stage for commercial SEMs in combination with automated established electron backscatter diffraction (EBSD) data acquisition is presented. This novel experimental setup can be used to achieve more information about microstructure and orientation changes during grain growth, recrystallization, recovery, and phase transformations. First results on theα−γ−αphase transformation in steel within886∘C–900∘C are presented.

Strain relaxed Si1−xGex buffer layers are of great importance as virtual substrates for Si1−xGex/Si quantum well structures and devices. We apply He+ ion implantation and subsequent annealing on pseudomorphic, MBE-grown Si1−xGex/Si(100) heterostructures with an implantation depth of about 100 nm below the Si1−xGex/Si interface. A narrow defect band is generated inducing the formation of strain relieving misfit dislocations during subsequent thermal annealing. Efficient strain relaxation was demonstrated for Si1−xGex layers with Ge fractions up to 30 at. %. The variation of the implantation dose and the annealing conditions changes the dislocation configuration and the He bubble structure. At a dose of 2×1016 cm−2 a high degree of relaxation is accompanied by a low density of threading dislocations of about 107 cm−2 for a Ge content of 30%. An additional increase of the Ge content can be achieved by annealing in oxygen. The oxidation of Si1−xGex leads to the formation of SiO2 while the Ge atoms are rejected from the oxide leading to a pile-up of Ge below the oxidation front. The heterostructures were analyzed using X-ray diffraction, Rutherford backscattering/channeling spectrometry and transmission electron microscopy.