Takashi Emoto

Strain field observed at the SiO2/Si(111) interface

Abstract The change of the strain field near the SiO2/Si(111) interface during removal of an oxide layer was investigated by X-ray diffraction under ultra high vacuum conditions. It was observed that the width of the rocking curve for the 311 plane became narrow during thinning of the oxide layer. From a theoretical consideration, it was found that the width of rocking curve depends upon the thickness of oxide layer, even if there is no strain field at the interface. This behavior of the width is mainly due to an absorption effect of X-rays in the oxide layer. By using a resultant equation, the intrinsic curve, containing only the strain effect, was obtained by deconvoluting the absorption effect from the experimental curve. From the result, it was concluded that the strain field near the interface relaxes for thinning of the oxide layer. The strain field near the Si(111) 7×7 surface is concluded to be smaller than that of the SiO2/Si(111) interface.

Strain near SiO2–Si interface revealed by X-ray diffraction intensity enhancement

Abstract For the system of polycrystalline Si/SiO 2 (thermal)/Si(001), the strain field introduced into the Si substrate was studied with the asymmetric X-ray diffraction method. Polycrystalline Si layers with a thickness of 10.0 nm were grown on 4.5-nm thick thermally grown oxide layers. To study the strain fields, the rocking curves for Si {113} planes of the bulk films were measured. The intensity of the rocking curves increased for polycrystalline Si-grown films, whereas the intensity must be decreased by the absorption of X-rays in the polycrystalline Si layer. This indicates that the strain is introduced into the substrate. The Darwin dynamical calculation for a distorted crystal indicates that the intensity enhancement of a rocking curve can occur as a compressive strain. From a comparison of the measured and calculated curves, we conclude that the compression of the {001} spacing near the substrate surface occurs during the growth of the polycrystalline Si layer.

Observation of the strain field near the Si(111) 7 × 7 surface with a new X‐ray diffraction technique

A new X-ray diffraction technique has been developed in order to measure the strain field near a solid surface under ultrahigh vacuum (UHV) conditions. The X-ray optics use an extremely asymmetric Bragg-case bulk reflection. The glancing angle of the X-rays can be set near the critical angle of total reflection by tuning the X-ray energy. Using this technique, rocking curves for Si surfaces with different surface structures, i.e. a native oxide surface, a slightly oxide surface and an Si(111) 7 x 7 surface, were measured. It was found that the widths of the rocking curves depend on the surface structures. This technique is efficient in distinguishing the strain field corresponding to each surface structure.

Interface reconstructed structure of Ag/Si(1 1 1) revealed by X-ray diffraction

We studied a buried interface reconstructed structure of the Ag/Si(111)√3 x √3-Ag samples using grazing incidence X-ray diffraction with synchrotron radiation. We found that the √3 interface superstructure can be explained by an inequivalent-triangle (IET) model, which has been observed on the Si(111)√3 x √3-Ag surface at low substrate temperatures by STM. The calculated structure factors of the IET model were found to be very close to our observed ones. The reliability factor (R-factor) using the IET model was about 25%. The R-factor was improved to be much less value, 12% by considering defects of Ag atoms forming the √3 structure. The Patterson map expected from the IET model having the defects was very similar to that calculated from the observed structure factors.

Crystal Orientation of Silver Films on Silicon Surfaces Revealed by Surface X-Ray Diffraction

We have studied the crystal orientation of Ag thin films on a

SURFACE AND INTERFACE STRAINS REVEALED BY X-RAY DIFFRACTION

{\rm Si}(111)(\sqrt{3} \times \sqrt{3})\mbox{-Ag}

Soft X-ray emissions by highly charged ions on solid surfaces : Mo and Ta surfaces

surface using grazing incidence X-ray diffraction with synchrotron radiation. After preparation of a

Strain due to nickel diffusion into hydrogen-terminated Si(1 1 1) surface

{\rm Si}(111)(\sqrt{3} \times \sqrt{3})\mbox{-Ag}

Quantitative evaluation of strain near reconstructed Si surfaces

surface, 50 ML Ag was deposited on the

Strain Relaxation at Semiconductor Surface Revealed by Extremely Asymmetric X-Ray Diffraction

{\rm Si}(111)(\sqrt{3} \times \sqrt{3})\mbox{-Ag}