Silicon surfaces which had been exposed to
CF4/40%H2
reactive ion etching have been characterized by x‐ray photoelectron emission spectroscopy, He ion channeling, H profiling, and Raman scattering techniques. Plasma exposure of a clean Si surface leads to the deposition of a thin (∼30–50Å thick) C,F containing film. The near‐surface region (∼30–50Å) of the Si substrate is heavily disordered (“amorphized”), as found by ion channeling and Raman scattering. A modified, less damaged Si region extends from about 30–50Å from the surface to a depth in excess of 250Å. This layer contains a high concentration (∼5 atom percent) of H as shown by hydrogen profiling techniques. From the observation of Si‐H and
normalSi‐H2
vibrational modes by Raman scattering, it has been shown that the H is bonded to the Si lattice. In ion scattering, the extended modified Si layer appears to cause a strongly enhanced background in the energy spectra. Results of Monte Carlo range calculations are reported and compared with the damage depth found experimentally.
We have measured the resonant tunneling current-voltage I(V) characteristics of strained p-Si/Si 1Ϫx Ge x double-barrier microstructures ranging from 1.0 to 0.1 m in lateral extent. The bias spacing between resonant current peaks in the I(V) reflects the energy separation of the Si 1Ϫx Ge x quantum well subbands, which is partially determined by the strain. As the lateral size of the structures decreases, we observe consistent shifts in the I(V) peak spacing corresponding to strain energy relaxation of ϳ30% in smaller structures. An additional I(V) fine structure is observed in the 0.1 m device, consistent with lateral quantization due to nonuniform strain.
In the present paper structural and chemical changes which can occur in the surface and near-surface properties of the substrate during anisotropic dry etching of SiO2 on Si will be reviewed.Silicon specimens which had been etched in CF4/X%H2 (X≤40) have been characterized by X-ray photoelectron emission spectroscopy, He ion channeling, H profiling and Raman scattering techniques.Key results of our studies are summarized as follows: Plasma exposure of a Si surface leads to the deposition of a thin (≤50Å thick) C,F-film.A Si-carbide containing Si region is formed during RIE which is localized near the fluorocarbon-film/Si interface.The near-surface region (∼30–50Å) of the Si substrate is also heavily disordered as found by ion channeling and Raman scattering.A modified, less damaged Si region has been found in the case of hydrogen-based etching gases, which extends from about 30–50Å from the surface to a depth in extent of 250Å and contains a high concentration (∼ 5 at.%) of H as shown by hydrogen profiling techniques.From the observation of Si-H and Si-H2 vibrational modes by Raman scattering it has been shown that some of the H is bonded to the Si lattice.
C+ and N+ implantation into type IIa diamond are performed at various temperatures (25 to 1000°C) and ion‐induced damage is studied by EPR measurements at 1.2 to 300 K. Hot implantation at 1000°C results in a reduced spin density of “amorphous” carbon by an order of magnitude less than that due to cold‐implantation and a subsequent annealing at 1000°C. Moreover, hot implantation above 600°C produces two new spin‐1 centers, A‐5 and A‐6, which are tentatively identified as a small multivacancy cluster.
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