The Experts below are selected from a list of 32055 Experts worldwide ranked by ideXlab platform
Matty Caymax - One of the best experts on this subject based on the ideXlab platform.
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Germanium Surface passivation and atomic layer deposition of high k dielectrics a tutorial review on Ge based mos capacitors
Semiconductor Science and Technology, 2012Co-Authors: Shaoren Deng, Matty Caymax, Marc Schaekers, Annelies Delabie, Xinping Qu, Yulong Jiang, Davy Deduytsche, Christophe DetavernierAbstract:Due to its high intrinsic mobility, Germanium (Ge) is a promising candidate as a channel material (offering a mobility gain of approximately??2 for electrons and??4 for holes when compared to conventional Si channels). However, many issues still need to be addressed before Ge can be implemented in high-performance field-effect-transistor (FET) devices. One of the key issues is to provide a high-quality interfacial layer, which does not lead to substantial drive current degradation in both low equivalent oxide thickness and short channel regime. In recent years, a wide ranGe of materials and processes have been investigated to obtain proper interfacial properties, including different methods for Ge Surface passivation, various high-k dielectrics and metal gate materials and deposition methods, and different post-deposition annealing treatments. It is observed that each process step can significantly affect the overall metal?oxide?semiconductor (MOS)-FET device performance. In this review, we describe and compare combinations of the most commonly used Ge Surface passivation methods (e.g. epi-Si passivation, Surface oxidation and/or nitridation, and S-passivation) with various high-k dielectrics. In particular, plasma-based processes for Surface passivation in combination with plasma-enhanced atomic layer deposition for high-k depositions are shown to result in high-quality MOS structures. To further improve properties, the gate stack can be annealed after deposition. The effects of annealing temperature and ambient on the electrical properties of the MOS structure are also discussed.
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Selective Area Growth of InP and Defect Elimination on Si (001) Substrates
Journal of The Electrochemical Society, 2011Co-Authors: Gang Wang, Wei-e Wang, Niamh Waldron, Olivier Richard, Guy Brammertz, Maarten Leys, Hugo Bender, Johan Dekoster, Matty CaymaxAbstract:We report the selective area growth of InP layers in submicron trenches on Si (001) substrates by using a thin Ge buffer layer. The antiphase domain boundaries in InP layers are suppressed by engineering the local Ge Surface profile. The mechanism of atomic step formation and the corresponding method for step density control are presented. We discuss the impact of the Surface profile of the Ge buffer layer on the formation of antiphase domain boundaries as well as on InP nucleation. A minimum step density of 0.25 nm ―1 is required to avoid antiphase domain boundaries while a higher step density substantially reduces the stacking faults and twins in the InP nucleation layer. By employing the threading dislocation necking effect and the properly controlled Ge Surface profile, high-quality InP layers have been obtained in submicron trenches.
Gang Wang - One of the best experts on this subject based on the ideXlab platform.
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Selective Area Growth of InP and Defect Elimination on Si (001) Substrates
Journal of The Electrochemical Society, 2011Co-Authors: Gang Wang, Wei-e Wang, Niamh Waldron, Olivier Richard, Guy Brammertz, Maarten Leys, Hugo Bender, Johan Dekoster, Matty CaymaxAbstract:We report the selective area growth of InP layers in submicron trenches on Si (001) substrates by using a thin Ge buffer layer. The antiphase domain boundaries in InP layers are suppressed by engineering the local Ge Surface profile. The mechanism of atomic step formation and the corresponding method for step density control are presented. We discuss the impact of the Surface profile of the Ge buffer layer on the formation of antiphase domain boundaries as well as on InP nucleation. A minimum step density of 0.25 nm ―1 is required to avoid antiphase domain boundaries while a higher step density substantially reduces the stacking faults and twins in the InP nucleation layer. By employing the threading dislocation necking effect and the properly controlled Ge Surface profile, high-quality InP layers have been obtained in submicron trenches.
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selective area growth of inp in shallow trench isolated structures on off axis si 001 substrates
Journal of The Electrochemical Society, 2010Co-Authors: Gang Wang, Olivier Richard, Guy Brammertz, Maarten Leys, Hugo Bender, Johan Dekoster, Marc Meuris, Ngoc Duy Nguyen, R Loo, Marc HeynsAbstract:In this paper, we report a comprehensive investigation of InP selective growth in shallow trench isolation (STI) structures on Si(001) substrates 6° off-cut toward (111). Extended defect-free InP layers were obtained in the top region of 100 nm wide trenches. A thin Ge epitaxial layer was used as an intermediate buffer layer between the Si substrate and the InP layer. A Ge buffer was used to reduce the thermal budGet for Surface clean and to promote double-step formation on the Surfaces. Baking the Ge Surface in an As ambient improved the InP Surface morphology and crystalline quality. InP showed highly selective growth in trenches without nucleation on SiO 2 . However, strong loading effects were observed at all growth pressures, which induced variation in local growth rates. We found trench orientation dependence of facet and stacking fault formation. More stacking faults and nanotwins originated from the STI sidewalls in [110] trenches. High quality InP layers were obtained in the top of the trenches along [110]. The stacking faults Generated by the dissociation of threading dislocations are trapped at the bottom of the trenches with an aspect ratio greater than 2.
Jinhua Chen - One of the best experts on this subject based on the ideXlab platform.
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triple helix molecular switch electrochemical ratiometric biosensor for ultrasensitive detection of nucleic acids
Analytical Chemistry, 2017Co-Authors: Erhu Xiong, Xiaohua Zhang, Jiawan Zhou, Xiaoxia Yan, Yunqing Liu, Jinhua ChenAbstract:Biomolecular receptors such as nucleic acids that switch between two or more conformations upon binding to a specific tarGet can be used to build specific and sensitive biosensors. In this work, based on the electrochemical dual-signaling ratiometric strategy and triple-helix molecular switch, we developed a selective, reusable, and simple electrochemical DNA (E-DNA) biosensor for tarGet DNA (T-DNA) detection. A hairpin DNA capture probe labeled with methylene blue (MB-DNA) self-assembles on the Surface of a gold electrode (Ge) through Au–S bond, and then a single-strand DNA modified with two ferrocenes (Fc-DNA) on each end to enhance the oxidation signal hybridizes with the MB-DNA to form a triple-helix conformation. When T-DNA exists, the Fc-DNA hybridizes with T-DNA disassembling the triple-helix stem and allowing the MB-DNA to revert to its hairpin structure. Hence, the Fc tags diffuse away from the Ge Surface while the MB tags remain affixed close to it, resulting in a decrease in the peak current of...
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Triple-Helix Molecular Switch Electrochemical Ratiometric Biosensor for Ultrasensitive Detection of Nucleic Acids
2017Co-Authors: Erhu Xiong, Xiaohua Zhang, Jiawan Zhou, Xiaoxia Yan, Yunqing Liu, Jinhua ChenAbstract:Biomolecular receptors such as nucleic acids that switch between two or more conformations upon binding to a specific tarGet can be used to build specific and sensitive biosensors. In this work, based on the electrochemical dual-signaling ratiometric strategy and triple-helix molecular switch, we developed a selective, reusable, and simple electrochemical DNA (E-DNA) biosensor for tarGet DNA (T-DNA) detection. A hairpin DNA capture probe labeled with methylene blue (MB-DNA) self-assembles on the Surface of a gold electrode (Ge) through Au–S bond, and then a single-strand DNA modified with two ferrocenes (Fc-DNA) on each end to enhance the oxidation signal hybridizes with the MB-DNA to form a triple-helix conformation. When T-DNA exists, the Fc-DNA hybridizes with T-DNA disassembling the triple-helix stem and allowing the MB-DNA to revert to its hairpin structure. Hence, the Fc tags diffuse away from the Ge Surface while the MB tags remain affixed close to it, resulting in a decrease in the peak current of Fc (IFc) and an increase in that of MB (IMB). The linear relationship between the value of IMB/IFc and the T-DNA concentration is observed from 0.5 to 80 pM, and the limit of detection is as low as 0.12 pM. The developed E-DNA biosensor may have great potential in the electrochemical detection of a wide ranGe of analytes and be a biosensing platform for early clinical diagnosis and biomedical research
L Clavelier - One of the best experts on this subject based on the ideXlab platform.
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epitaxial growth of Ge thick layers on nominal and 6 off si 0 0 1 Ge Surface passivation by si
Semiconductor Science and Technology, 2009Co-Authors: J M Hartmann, Alexandra Abbadie, N Cherkashin, H Grampeix, L ClavelierAbstract:We have grown various thickness Ge layers on nominal and 6? off Si(0?0?1) substrates using a low-temperature/high-temperature strategy followed by thermal cycling. A combination of 'mounds' and a perpendicular cross-hatch were obtained on nominal Surfaces. On 6? off Surfaces, three sets of lines were obtained on top of the 'mounds': one along the 1?1?0 direction perpendicular to the misorientation direction and the other two at ~4.5? on each side of the 1?1?0 direction parallel to the misorientation direction. The Surface root mean square roughness was less than 1 nm for 2.5 ?m thick nominal and 6? off Ge layers. Those slightly tensily strained Ge layers (R ~ 104%) were characterized by 5 ? 107 cm?2 (as-grown layers) ?107 cm?2 (annealed layers) threading dislocation densities, independently of the substrate orientation. We have then described the 550 ?C/650 ?C process used to passivate nominal Ge(0?0?1) Surfaces with Si prior to gate stack deposition. An ~5 ? thick SiGe interfacial layer is self-limitedly grown at 550 ?C and then thickened at 650 ?C (5 ? min?1) thanks to SiH2Cl2 at 20 Torr. Such a Ge Surface passivation yields state-of-the-art p-type metal oxide semiconductor field effect transistors provided that 15 ? Si layer thickness is not exceeded. For higher thickness, elastic strain relaxation (through the formation of numerous 2D islands) occurs, followed by plastic relaxation (for a 35 ? thick Si layer).
Hongjie Dai - One of the best experts on this subject based on the ideXlab platform.
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Surface chemistry and electrical properties of Germanium nanowires
Journal of the American Chemical Society, 2004Co-Authors: Dunwei Wang, Yinglan Chang, Qian Wang, Jien Cao, Damon B Farmer, Roy G Gordon, Hongjie DaiAbstract:Germanium nanowires (GeNWs) with p- and n-dopants were synthesized by chemical vapor deposition (CVD) and were used to construct complementary field-effect transistors (FETs). Electrical transport and X-ray photoelectron spectroscopy (XPS) data are correlated to glean the effects of Ge Surface chemistry to the electrical characteristics of GeNWs. LarGe hysteresis due to water molecules strongly bound to GeO(2) on GeNWs is revealed. Different oxidation behavior and hysteresis characteristics and opposite band bending due to Fermi level pinning by interface states between Ge and Surface oxides are observed for p- and n-type GeNWs. Vacuum annealing above 400 degrees C is used to remove Surface oxides and eliminate hysteresis in GeNW FETs. High-kappa dielectric HfO(2) films grown on clean GeNW Surfaces by atomic layer deposition (ALD) using an alkylamide precursor is effective in serving as the first layer of Surface passivation. Lastly, the depletion length along the radial direction of nanowires is evaluated. The result sugGests that Surface effects could be dominant over the "bulk" properties of small diameter wires.
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Surface chemistry and electrical properties of Germanium nanowires
Journal of the American Chemical Society, 2004Co-Authors: Dunwei Wang, Yinglan Chang, Qian Wang, Jien Cao, Damon B Farmer, Roy G Gordon, Hongjie DaiAbstract:Germanium nanowires (GeNWs) with p- and n-dopants were synthesized by chemical vapor deposition (CVD) and were used to construct complementary field-effect transistors (FETs). Electrical transport and X-ray photoelectron spectroscopy (XPS) data are correlated to glean the effects of Ge Surface chemistry to the electrical characteristics of GeNWs. LarGe hysteresis due to water molecules strongly bound to GeO2 on GeNWs is revealed. Different oxidation behavior and hysteresis characteristics and opposite band bending due to Fermi level pinning by interface states between Ge and Surface oxides are observed for p- and n-type GeNWs. Vacuum annealing above 400 °C is used to remove Surface oxides and eliminate hysteresis in GeNW FETs. High-κ dielectric HfO2 films grown on clean GeNW Surfaces by atomic layer deposition (ALD) using an alkylamide precursor is effective in serving as the first layer of Surface passivation. Lastly, the depletion length along the radial direction of nanowires is evaluated. The result s...
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Surface chemistry and electrical properties of Germanium nanowires
arXiv: Materials Science, 2004Co-Authors: Dunwei Wang, Yinglan Chang, Qian Wang, Jien Cao, Damon B Farmer, Roy G Gordon, Hongjie DaiAbstract:Germanium nanowires with p- and n-dopants were synthesized by chemical vapor deposition and used to construct complementary field effect transistors . Electrical transport and x-ray photoelectron spectroscopy data are correlated to glean the effects of Ge Surface chemistry to the electrical characteristics of GeNWs. LarGe hysteresis due to water molecules strongly bound to GeO2 on GeNWs is revealed. Different oxidation behavior and hysteresis characteristics and opposite band bending due to Fermi level pinning by interface states between Ge and Surface oxides are observed for p- and n-type GeNWs. Vacuum annealing above 400C is used to remove Surface oxides and eliminate hysteresis in GeNW FETs. High-k dielectric HfO2 films grown on clean GeNW Surfaces by atomic layer deposition (ALD) using an alkylamide precursor is effective serving as the first layer of Surface passivation. Lastly, the depletion length along the radial direction of nanowires is evaluated. The result sugGests that Surface effects could be dominant over the bulk properties of small diameter wires.
