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GaAs/Ge crystals grown on Si substrates patterned down to the micron scale
Full text linkMonolithic integration of III-V compounds into high density Si
integrated circuits is a key technological challenge for the next
generation of optoelectronic devices. In this work, we report on the
metal organic vapor phase epitaxy growth of strain-free GaAs crystals on
Si substrates patterned down to the micron scale. The differences in
thermal expansion coefficient and lattice parameter are adapted by a
2-mu m-thick intermediate Ge layer grown by low-energy plasma enhanced
chemical vapor deposition. The GaAs crystals evolve during growth
towards a pyramidal shape, with lateral facets composed of \111\
planes and an apex formed by \137\ and (001) surfaces. The influence
of the anisotropic GaAs growth kinetics on the final morphology is
highlighted by means of scanning and transmission electron microscopy
measurements. The effect of the Si pattern geometry, substrate
orientation, and crystal aspect ratio on the GaAs structural properties
was investigated by means of high resolution X-ray diffraction. The
thermal strain relaxation process of GaAs crystals with different aspect
ratio is discussed within the framework of linear elasticity theory by
Finite Element Method simulations based on realistic geometries
extracted from cross-sectional scanning electron microscopy images. (C)
2016 AIP Publishing LLC
Procedimento per la fabbricazione di canali nanometrici
No full textBrevetto Politecnico di Milano TO 2008 A 39
Plasma composition by mass spectroscopy in a Ar-SiH4-H 2 LEPECVD process during nc-Si deposition
No full textPlasma composition by mass spectroscopy in a Ar-SiH4-H 2 LEPECVD process during nc-Si depositio
Plasmon-enhanced Ge-based metal-semiconductor-metal photodetector at near-IR wavelengths
Full text linkWe demonstrate the use of plasmonic effects to boost the near-infrared sensitivity of metal-semiconductor-metal detectors. Plasmon-enhanced photodetection is achieved by properly optimizing Au interdigitated electrodes, micro-fabricated on Ge, a semiconductor that features a strong near IR absorption. Finite-difference time-domain simulations, photocurrent experiments and Fourier-transform IR spectroscopy are performed to validate how a relatively simple tuning of the contact geometry allows for an enhancement of the response of the device adapting it to the specific detection needs. A 2-fold gain factor in the Ge absorption characteristics is experimentally demonstrated at 1.4 µm, highlighting the potential of this approach for optoelectronic and sensing applications.QCD/Scappucci La
Ultrathin Fe films on single crystal and virtual Ge(001) substrates: towards the control of magnetic properties
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