Yuji C. Sasaki

Refraction effect of scattered X-ray fluorescence at surface

The angular distribution of X-ray fluorescence shows anisotropic radiation. We proved that the origin of the anisotropic radiation is X-ray refraction by using a scattered X-ray fluorescence model. Utilizing the refraction effect of X-ray fluorescence, we can obtain much information: for example, surface density, chemical condition, surface roughness, and particle diameter of element, as a new tool of studying surfaces and interfaces. We introduce a new X-ray dispersive system utilizing X-ray refraction.

New nondestructive depth profile measurement by using a refracted x‐ray fluorescence method

We demonstrated analysis of the nondestructive depth profile near the surface of As ion‐implanted Si substrate by using the refracted x‐ray fluorescence method. Experimental results show that the angular distribution of the measured x‐ray fluorescence is dependent on the surface roughness of the substrate.

Refracted X-ray Fluorescence (RXF) on Si single crystal and GaAs

The Refracted X-ray Fluorescence (RXF) method can obtain the information about surfaces and interfaces: for example, surface electron density, chemical condition and surface roughness. We evaluated surfaces and interfaces of ultrathin films by using RXF method, and we measured the average lattice constant of a ultrathin GaAs film, the top-layer of a GaAs substrate and the surface roughness of the Si substrate below a ultrathin GaAs film grown by MBE.

New technique for evaluation of surfaces and interfaces at atmospheric pressure by using Refracted X-ray Fluorescence (RXF)

Abstract Refracted X-ray fluorescence (RXF) can evaluate thin films at atmospheric pressure. In this letter, we show the possibility of in-situ evaluation of surfaces and interfaces in atmospheric-pressure metal-organic chemical vapor deposition (AP-MOCVD) and atmospheric-pressure metal-organic vapor phase epitaxy (AP-MOVPE) by using the refracted X-ray fluorescence (RXF) technique. Evaluation at atmospheric pressure is illustrated by an example of evaporated metal thin films.

Analysis of THz-wave difference-frequency generation in two- dimensional domain-inverted structure

We present theoretical and experimental results of surface-emitted THz-wave difference frequency generation (DFG) in 2 dimensional (D) periodically poled lithium niobate (PPLN) crystal. The two orthogonal periodic structures compensate the phase mismatch in two mutually perpendicular directions of the optical and THz-wave propagation. The tunable 1.5 - 1.8 THz wave generation with impulse power of 0.1 mW and repetition rate 1 MHz is obtained. The opportunity of the power enhancement using an interference of THz fields generated by the both forward and backward propagating optical waves is investigated. The power and radiation pattern of generated of THz-wave are calculated in far-field approximation. Analysis of THz-wave DFG in 2D PPLN and its correlation with experimental data is presented.