Laurent Clavelier

Growth of InAs/GaAs quantum dots on germanium-on-insulator-on-silicon (GeOI) substrate with high optical quality at room temperature in the 1.3 μm band

We report the growth of self-assembled InAs/GaAs quantum dots (QDs) on germanium-on-insulator-on-silicon (GeOI) substrate by metal organic chemical vapor deposition. We demonstrate that the introduction of a single QD layer can act as an anti-phase-domain filter resulting in GaAs/GeOI layers with high structural quality and low surface roughness. High density (4×1010u2002cm−2) QDs were obtained with emission at 1.3u2002μm, narrow peak linewidth (33 meV), and identical photoluminescence intensity at room temperature similar to QDs obtained on conventional GaAs substrate. These results show the feasibility of the GeOI platform for the monolithic integration of QD-based lasers on silicon.

Effect of Antimony on the Photoluminescence Intensity of InAs Quantum Dots Grown on Germanium-on-Insulator-on-Silicon Substrate

We report on the antimony (Sb) surfactant-mediated growth of InAs quantum dots (QDs) on a germanium-on-insulator-on-silicon (GeOI) substrate. A GaAs buffer layer of high structural quality and low surface roughness was first grown on a GeOI substrate. The dependence of Sb irradiation time on the photoluminescence intensity and total density of InAs/Sb:GaAs QDs grown on a GeOI was studied. High density (above 6×1010 cm-2) QDs with ground state emission in the 1.3 µm band at room temperature and narrow linewidth (32 meV) was obtained. Together, these results are very promising for potential realization of monolithically integrated QD-based lasers on silicon.

Investigating Electronic and Chemical Properties of Ge/GeOxNy/HfO2 Gate Stacks : High-Resolution Photoelectron Spectroscopy Using Synchrotron Radiation

Photoelectron spectroscopy is extremely suitable for probing the basic properties of advanced gate stacks and investigate the compatibility between new materials introduced in post-32 nm node CMOS device technology. Implementing photoelectron spectroscopy with soft x-rays delivered by synchrotron sources brings uncomparable benefits for the study of advanced gate stacks in terms of energy resolution and detection limits [1, 2, 3]. The energy tunability enables simultaneously valence band and core-level studies for respectively information about the electronics (band offsets, band bending, electronic states in the gate oxide band gap) and chemical properties (chemical bonding states) of the materials and their interfaces. We present recent results of a soft x-ray photoelectron spectroscopy study of Ge/GeON/HfO2 gate stacks obtained at the ELETTRA synchrotron source (Italy). High-resolution (overall energy resolution 50 meV) valence band spectra, acquired at 160 and 80 eV photon energy, show up the extension of localized electronic states into the Ge oxide band gap and a very faint structure near the Fermi level related to Ge 4p states forming the top of the Ge substrate valence band (fig. 1), allowing the determination of the Ge/GeON valence band offset. Upon HfO2 deposition the offset between the Ge gate and the gate oxide is reduced by 2eV. These results are important for assessing the reliability of such gate stacks for advanced CMOS applications. Complementary core-level results will be also presented in terms of bonding state analysis at the GeON/HfO2 interace, highlighting the benefit of synchrotron radiation for a fine tuning of the sampling depth using the photon energy tenability.