Noriyuki Aizawa

Ultra-Large-Scale Step-Free Terraces Formed at the Bottom of Craters on Vicinal Si(111) Surfaces.

We report the self-controlled planarization of Si(111) surfaces at the bottom of craters. A (111) plane with a step spacing as large as 10 micrometers can be obtained at the bottom of a crater by heating a misoriented Si(111) substrate with craters at around 1200°C in ultrahigh vacuum. The (111) plane grows preferentially by filling adatoms in the crater until the plane surface reaches one of the top edges of the crater. The resulting surface has an extremely small miscut angle (<0.002°), making it useful for fundamental research into crystal growth as well as for device fabrication.

Magnetostriction observed by X-ray diffraction in iron

A new technique to observe magnetostriction by X-ray diffraction was reported. We found that a symmetry part of the relative diffraction intensity change induced by applying magnetic field was proportional to a Bragg angle shift. It was a differential measurement on the rocking curve. The Bragg angle and its shift gave quantitative magnetostrictive coefficients. Sensitivity of the present method on the magnetostrictive coefficient for an iron specimen approached to 10/sup -7/.

X-ray diffraction technique to observe magnetostriction and magnetization at coextensive volumes of iron

We present a new technique for observing both magnetostriction and magnetization as a function of applied magnetic field strength. They are simultaneously measured by the same X-ray probes with a goniometer at exactly coextensive specimen volumes. The measurements yield experimental magnetostriction curves during a cyclic magnetization process in iron (100) single-crystal specimen at room temperature. The technique is a new tool to investigate magnetic properties within X-ray extinction depth from the surface.

Direct evidence for Ge preferential growth at steps and out-of-phase boundaries of (7×7) domains on Si(111) in solid phase epitaxy

Abstract Ge solid phase epitaxy on a Si(111) surface has been directly observed by secondary electron surface microscopy which is based on scanning electron microscopy. Ge island formation initially occurs at steps and out-of-phase boundaries of (7 × 7) domains. These results confirm the origin of previously reported mesh patterns of Ge islands grown on Si(111).

Electron Microscopy Study of Surfactant-Mediated Solid Phase Epitaxy of Ge on Si(111)

The effect of As surfactant on solid phase epitaxy (SPE) of Ge on Si(111) has been investigated using in situ scanning electron microscopy and ex situ transmission electron microscopy. As surfactant is supplied to an amorphous Ge film in four different ways: co-deposition with the Ge film, deposition on the Si substrate, deposition on each interface of 3-nm-thick Ge films in a multilayered structure, and deposition on the surface of a Ge film. As at the Ge/Si interface has a limited effect in suppressing island growth with a critical thickness of about 20 monolayers (ML). Thicker film growth is achieved by the other three SPE methods. Although the surface morphology slightly differs, the crystalline quality is almost the same for all cases. An As surfactant on the surface of amorphous Ge increases the crystallization temperature by 100°C compared to the Ge islands temperature without As. This indicates that an As overlayer inhibits structural relaxation on amorphous film by suppressing surface diffusion of Ge atoms, thus changing the growth mode. In other SPE methods, surface passivation with As due to segregation during deposition may also be responsible for the suppression of islands.

Effect of surfactant on Ge crystallization on Si in solid phase epitaxy

Abstract We have studied the influence of surfactant on solid phase epitaxy of an amorphous Ge layer on Si(111) using in situ scanning electron microscopy. A monolayer of As overlayer deposited on the amorphous Ge layer raises the Ge crystallization temperature by up to 100 K both on 7 × 7 and “1 × 1” regions, as well as suppresses islanding of Ge. The crystallization temperature raise is discussed as pining of the surface by As inhibiting the movement of excess volume during crystallization of the amorphous Ge layer.

Geometrical Surface Wave Resonance at a Silicon (111) Surface in Reflection High-Energy Electron Diffraction

The geometrical surface wave resonance condition in reflection high-energy electron diffraction (RHEED) is determined experimentally at the [10] azimuth on a (111) surface of a silicon single crystal. The surface at this azimuth is a non-mirror plane of the crystal lattice for RHEED. The condition for this surface is verified as similar to that of a mirror plane.

Magnetostriction Observation with Synchrotron Radiation

In this study, the magnetostriction curve as a function of the relative magnetization applying the magnetic field along [-1 1 2] of an iron specimen was observed and discussed. The X-ray diffraction technique to observe the magnetostriction and the relative magnetization could determine whether the magnetostriction curves have the hysteresis.

Internal magnetostriction observed by X-ray diffraction in iron

A new technique to observe the internal mode of the magnetostriction with sufficient sensitivity using X-ray diffraction was developed. As a result, the antisymmetry part of the diffraction intensity change was proportional to a flipping ratio of an X-ray magnetic diffraction (XMD). This technique using X-rays has the potential to simultaneously investigate magnetostriction together with XMD at local coextensive specimen volumes.