We have analyzed the strain distribution and the photoluminescence in Ge microstructures fabricated by means of a Si-CMOS compatible method. The tensile strain in the Ge microstructures is obtained by using a SiN stressor layer. Different shapes of microstructure, allowing the Ge layers to freely expand into one, two, or three dimensions, resulted in different strain distribution profiles. Maximal equivalent biaxial tensile strain values up to ~0.8% have been measured. Room temperature photoluminescence emission has been observed and attributed to direct-band gap recombination spectrally shifted by tensile strai

Ge/Si(001) heterostructures grown by means of ultrahigh vacuum chemical vapor deposition have been investigated by means of variable temperature high resolution x ray diffraction in order to investigate the origin of the residual tensile strain observed in this system. To this purpose, we have simultaneously measured the in- and out-of-plane lattice parameters of the deposited Ge films and of the underlying Si substrate, thus allowing us to directly measure the Ge strain evolution as the epilayer was annealed up to and over the deposition temperature and cooled back to room temperature. We have observed that the tensile strain, resulting from the different Si and Ge thermal expansion coefficient, is partially compensated by the residual compressive heteroepitaxial strain, due to the hardening limit of Ge. This limited the tensile strain observable in these heterostructures to ∼0.002. © 2012 American Institute of Physics

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Thin BaHfO3 dielectric films were investigated in view of future dynamic random access memory applications. The dielectric layers were prepared by physical vapor codeposition of BaO and HfO2 onto metallic TiN substrates. Films deposited at 400°C are amorphous, show low leakage [J(1V)<10−8A∕cm2] at capacitance equivalent thicknesses (CETs) down to ∼2nm and a dielectric constant of ∼23. Rapid thermal annealing of the amorphous BaHfO3 films induces crystallization in the cubic perovskite phase with a dielectric constant of ∼38. This k value was observed for films as thin as 8nm enabling CET value of ∼0.9nm.