Ken'ichi Ishikawa

A new system for two-dimensional analysis of hydrogen on solid surfaces

This article reports the development of a two-dimensional analyzer, which enables us to observe the distribution of hydrogen on surfaces. A micro-focused electron beam with low primary electron energy (<1 keV) is scanned over a sample surface, in conjunction with a time-of-flight type electron-stimulated desorption spectroscope, to obtain clear H+ ion images of a specimen surface. A line scan analysis of H+ ions on an integrated circuit and a scanning electron-stimulated desorption image of H+ ions on a Cu mesh are presented as demonstrations.

Two-dimensional hydrogen distribution on solid surfaces studied by electron-stimulated desorption microscopy and Ni-silicides on H-terminated Si(100) surfaces

Hydrogen termination of silicon dangling bonds is a useful method in large-scale integrated circuit (LSI) technology. In the present study, a two-dimensional (2D) hydrogen analyzer has been developed using an electron-stimulated desorption (ESD) method. A result of 2D hydrogen analysis revealed a spatial resolution of 700 nm under the optimal condition. Hydrogen termination has been applied to heteroepitaxial growth of a Ni-silicide system on the H-terminated Si(100) surface using a scanning tunneling microscope (STM). The H-terminated surface formed a sharp interface between the silicide and the substrate.

Two-Dimensional Hydrogen Analysis of Hydrogen Storage Alloy Surface by Electron-Stimulated Desorption Microscopy

Hydrogen analysis on the solid surfaces in an ultrahigh vacuum has been performed by electron stimulated desorption (ESD) microscopy. A scanning time-of-flight (TOF)-ESD measured a two-dimensional hydrogen distribution with a spatial resolution of less than 1 µm. Scanning TOF-ESD was applied to a hydrogen storage alloy surface (vanadium-titanium-nickel system) in order to measure the two-dimensional distribution of hydrogen. In the clear image, hydrogen is distributed mainly on the matrix of the vanadium surface and oxide layers localize on the titanium and nickel at grain boundaries.

Two-Dimensional Hydrogen Analysis on Solid Surfaces by Time-of-Flight Electron-Stimulated Desorption Microscope.

Hydrogen analysis on a solid surface has been performed using the electron-stimulated desorption (ESD) method. ESD is a highly sensitive technique for hydrogen analysis due to an isotope effect of desorbed ions. The scanning system of the ESD method which used a finely focused electron gun, reveals a two-dimensional hydrogen distribution on the surface. The spatial resolution is smaller than 1 µm. The degradation of petterning on the hydrogen terminated surface (a kind of radiation damage) by repeated scanning on the lithographed lines, related to the cross section of ion desorption, is discussed.

Time-resolved electron stimulated desorption microscope for two-dimensional hydrogen chemical states analysis

Abstract Adsorbed protium and hydrogen have different adsorption energies on different adsorbates due to different chemical bonding states. A time-of-flight type electron-stimulated desorption (TOF-ESD) measures different types of chemical bonding states of adsorbed hydrogen on the solid surfaces. Different kinetic energies of desorbed H+ are distinguished as different kinetic energies in the spectrum of TOF-ESD microscopy. Hydrogen chemical state analysis has been demonstrated for the first time using scanning ESD ion microscope on the modified line-and-space composite of Si and SiO2. In this report we describe a construction and analytical result of two kinds of hydrogen maps (also oxygen maps) corresponding to Si-line and SiO2-line with the spatial resolution of less than 1 μm .

New development of a high-resolution scanning ESD system for two-dimensional images of hydrogen and its applications

Abstract Currently, many people have focused their study of hydrogen behaviors on solid surfaces because this plays an important role in surface physics and chemistry. Hydrogen is detected easily by a time-of-flight type electron-stimulated desorption spectroscopy (TOF-ESD). Very recently, we have developed way to measure a two-dimensional distribution of hydrogen with high-resolution of less than 1 μm using a thermal field emission (TFE) electron gun. The high detection efficiency of the TOF-ESD system allows various ESD measurements including two-dimensional analysis. This method is complementary to scanning Auger electron microscopy (SAM), since SAM is insensitive to hydrogen but is able to analyze surface concentration for most elements. In this article, we show some results obtained by our TOF-ESD system using a LEED gun and a LaB6 gun and recent progress using a TFE gun.