Interaction of oxygen with a Ge-covered Si(100) surface

Surnev, S.

doi:10.1016/0039-6028(93)90606-k

Cited by 11 publications

(3 citation statements)

References 23 publications

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“…For example, the SEG of Si x Ge 1 - x (0 ≤ x < 1) has been demonstrated in chemical vapor deposition (CVD) systems, where a SiO 2 mask is used together with selectivity-controlling agents such as H and Cl. − The following surface phenomena are thought to be responsible for the selectivity in such CVD systems: (1) Cl etches Ge nuclei on SiO 2 . ,, (2) H absorbed on SiO 2 prevents Ge nucleation. ,, (3) Ge reacts with SiO 2 to form volatile SiO and GeO. , In molecular beam epitaxy (MBE) systems, where the selectivity controlling agents are often absent, the SEG of Si x Ge 1 - x on Si over a SiO 2 mask has also been demonstrated. ,− On the basis of the experimental observation that Ge molecular beam exposure removes ultrathin SiO 2 films, ,− the selectivity has been attributed to the reaction Ge + SiO 2 → GeO(g) + SiO(g), which does not require elemental Si. ,,− However, other findings contradict this mechanism at substrate temperatures less than 700 °C. First, oxygen transfer occurs from Ge to Si at elevated temperatures because the reaction enthalpy of oxygen with Si is larger than that of oxygen with Ge. ,, Second, if the starting materials are GeO 2 and Si, then the oxygen transfer from Ge to Si accelerates with increasing temperature, predominantly producing SiO 2 rather than volatile GeO and SiO . Third, Ge promotes SiO 2 degradation only in the presence of Si, and Ge alone does not degrade SiO 2 .…”

Section: Introductionmentioning

confidence: 99%

Probing Interactions of Ge with Chemical and Thermal SiO₂ to Understand Selective Growth of Ge on Si during Molecular Beam Epitaxy

2006

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We have previously demonstrated that Ge selectively grows on Si over a SiO2 mask during molecular beam epitaxy. To determine the surface phenomena responsible for the selectivity, we probed the stability of SiO2 upon Ge exposure and Ge diffusion through thin SiO2, using X-ray photoelectron spectroscopy, ellipsometry, atomic force microscopy, transmission electron microscopy, and multiple internal reflection Fourier transform infrared spectroscopy. We observe that the consumption of SiO2 occurs only with chemical oxide upon Ge exposure via Ge + Si + 2SiO2 → GeO(g) + 3SiO(g) at the SiO2/Si interface where all three reactants are present. This erosion is initiated by the Ge diffusion only through thin chemical SiO2, and the diffusion is attributed to a larger concentration of SiOH groups (∼1 × 1022 cm-3) and a greater porosity in chemical oxide than that in thermal oxide. For thermal SiO2, where Ge diffusion and subsequent oxide degradation are not observed, we have determined that the selectivity stems from the low desorption activation energy (E des) of Ge adspecies from the thermal SiO2 surface. The experimentally measured E des is 42 ± 3 kJ/mol on the order of Van der Waals force. The low E des entails a low activation barrier (∼13 kJ/mol) for the surface diffusion of Ge adspecies on thermal SiO2, leading to a characteristic diffusion length greater than 1 μm. Under typical Ge growth conditions where the interdistance between exposed Si areas is much less than 1 μm, the large diffusion length would cause Ge adspecies to migrate over SiO2 and preferentially aggregate on the exposed Si surface.

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Section: Introductionmentioning

confidence: 99%

Probing Interactions of Ge with Chemical and Thermal SiO₂ to Understand Selective Growth of Ge on Si during Molecular Beam Epitaxy

2006

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“…1) could indicate that Ge has been lost from the substrate during the silane-annealing step possibly by forming volatile GeO. Surnev [12] showed that GeO desorbed from a Ge-covered Si (1 0 0) substrate at 680-740 K when Ge was exposed to oxygen at 300 K. However, Surnev [12] also showed that oxygen could transfer from GeO x to Si when the surface was annealed between 370 and 850 K with complete reduction of the oxidized Ge to Ge 0 at 850 K. The silane-annealing temperature of 800 K is well above the temperature at which GeO desorption occurs and is also in the temperature range for GeO x reduction by Si. Because the Ge 0 increased by 43720%, it appears that the reduction of the hafnium germinate by Si adatoms is the dominant mechanism at our silane treatment conditions.…”

Section: Resultsmentioning

confidence: 97%

The role of oxidized germanium in the growth of germanium nanoparticles on hafnia

Winkenwerder¹,

Ekerdt²

2008

Journal of Crystal Growth

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“…We exclude work function changes due to oxidation of germanium 67 on the SiGe nano-stripes since no chemical shifted structures appears at the low kinetic energy side in the Ge 3d spectrum (see Fig. 2).…”

Section: Appendix B: Work Function Mappingmentioning

confidence: 99%

Hydrostatic strain enhancement in laterally confined SiGe nanostripes

et al. 2013

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Strain-engineering in SiGe nanostructures is fundamental for the design of optoelectronic devices at the nanoscale. Here we explore a new strategy, where SiGe structures are laterally confined by the Si substrate, to obtain high tensile strain avoiding the use of external stressors, and thus improving the scalability. Spectro-microscopy techniques, finite element method simulations and ab initio calculations are used to investigate the strain state of laterally confined Ge-rich SiGe nano-stripes. Strain information is obtained by tip enhanced Raman spectroscopy with an unprecedented lateral resolution of ~ 30 nm. The nano-stripes exhibit a large tensile hydrostatic strain component, which is maximum at the center of the top free surface, and becomes very small at the edges. The maximum lattice deformation is larger than the typical values of thermally relaxed Ge/Si(001) layers. This strain enhancement originates from a frustrated relaxation in the out-of-plane direction, resulting from the combination of the lateral confinement induced by the substrate side walls and the plastic relaxation of the misfit strain in the (001) plane at the SiGe/Si interface. The effect of this tensile lattice deformation at the stripe surface is probed by work function mapping, performed with a spatial resolution better than 100 nm using X-ray photoelectron emission microscopy. The nano-stripes exhibit a positive work function shift with respect to a bulk SiGe alloy, quantitatively confirmed by electronic structure calculations of tensile strained configurations. The present results have a potential impact on the design of optoelectronic devices at a nanometer length scale.Comment: 40 pages, 11 figures, submitted to Physical Review

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Interaction of oxygen with a Ge-covered Si(100) surface

Cited by 11 publications

References 23 publications

Probing Interactions of Ge with Chemical and Thermal SiO₂ to Understand Selective Growth of Ge on Si during Molecular Beam Epitaxy

Probing Interactions of Ge with Chemical and Thermal SiO₂ to Understand Selective Growth of Ge on Si during Molecular Beam Epitaxy

The role of oxidized germanium in the growth of germanium nanoparticles on hafnia

Hydrostatic strain enhancement in laterally confined SiGe nanostripes

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Interaction of oxygen with a Ge-covered Si(100) surface

Cited by 11 publications

References 23 publications

Probing Interactions of Ge with Chemical and Thermal SiO2 to Understand Selective Growth of Ge on Si during Molecular Beam Epitaxy

Probing Interactions of Ge with Chemical and Thermal SiO2 to Understand Selective Growth of Ge on Si during Molecular Beam Epitaxy

The role of oxidized germanium in the growth of germanium nanoparticles on hafnia

Hydrostatic strain enhancement in laterally confined SiGe nanostripes

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Product

Resources

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Probing Interactions of Ge with Chemical and Thermal SiO₂ to Understand Selective Growth of Ge on Si during Molecular Beam Epitaxy

Probing Interactions of Ge with Chemical and Thermal SiO₂ to Understand Selective Growth of Ge on Si during Molecular Beam Epitaxy