Kanji Masui

Analysis of Change in Optical Transmission Spectra Resulting from Ag Photodoping in Chalcogenide Film

Photodoping in a thin sample of Ag–Ge30S70 was studied by an optical transmission measurement. Changes in the optical transmission spectra were analyzed on the bases of a uniform distribution of dissolved Ag. This study suggests that the spectra of thin samples are not modulated by the interference effect over a wavelength range of 350–800 nm. The amount of photodoped Ag is quantitatively estimated from values of ln [T(t)/T(0)], where T(t) is the transmission after exposure to light for time t. There is a specific wavelength at which the transmission is practically independent of the irradiation time; traces of the spectra reach a point at this wavelength. This point is called an isotransmission point and is denoted λ*. The condition that λ* appears in the spectra was derived theoretically. The isotransmission point is useful for estimating the thicknesses of an Ag-doped layer.

Synthesis of PbS in aqueous solutions by photochemical reactions

Abstract PbS is successfully synthesized in aqueous solutions by photochemical reactions. The solution contains Pb(CH3COO)2 and Na2S2O3, and pH is controlled in an acidic region by adding H2SO4. The solution is irradiated with light from a high-pressure mercury-arc lamp. The PbS particles formed by the homogeneous nucleation in the solution are micro-crystalline and have nearly stoichiometric composition. PbS thin films are also formed on a Pd-treated glass sheet by the heterogeneous nucleation.

Formation of amorphous Al-transition metal (TM: Fe, Co, Ni) binary alloy films by RF-sputtering

A new type AlTM amorphous alloy was produced by RF-sputtering under Ar atmosphere. The existence of the amorphous phase was confirmed by X-ray diffraction, transmission electron microscopy, calorimetric and electrical resistivity measurements. It was found that the amorphous phase is formed in the limited composition range of about 75 to 90 at.% Al and the formation of the amorphous phase in such a limited composition range is closely associated with the existence of several intermetallic compounds (Fe4Al13, FeAl6, Co4Al13, Co2Al9, NiAl3) in nearly the same composition range having a crystallographically complex structure. The crystallization temperatures of the amorphous alloys are 360°C, 260°C and 220°C for AlFe, AlCo and AlNi alloys, respectively.

Photobleaching and thermal-bleaching effects in amorphous Ge-S films

Abstract The optical and structural changes in Ge 30 S 70 film by light irradiation and heat-treatment have been studied by optical transmission measurements, X-ray diffraction, ESR and ESCA. Photobleaching and thermal-bleaching effects are considered to result from the photo- and thermal-polymerizations, respectively, and they lead to the change in the network structure of the film. ESCA spectra of Ge3d suggest that photo-oxidation of Ge atom at the surface layer occurs by the illumination.

Evaluation and analysis of Ag photodoping in chalcogenide film by optical transmission measurement

Changes in the optical transmission spectra resulting from Ag photodoping in thin Ge30S70 film were analyzed on the basis of a uniform distribution of dissolved Ag. This study suggests that photodoping rate is quantitatively evaluated from time dependence of 1n[ T(t)/T(O) ] obtained from the spectra of thin photodoping sample, where T(t) is the transmission after exposure to light for time t . The relations between initial photodoping rate and photon energy of irradiated light were investigated for the irradiation of light from Ag-layer side and Ge30S70-layer side, respectively. The difference in the initial photodoping rate for the irradiated sides was interpreted on the basis of the intensities of light reached to the Ag-doped layer through the Ag layer and the Ge30S70 layer. The following results were obtained: (1) for the exposure to light with low photon energy, the light absorbed in the Ag-doped layer causes the photodoping; (2) for the exposure to light with high photon energy, the light absorbed in the chalcogenide layer causes mainly the photodoping; (3) our experimental results suggest that the light absorbed in the Ag layer is not effective in the photodoping.

Electron beam-induced structural changes in amorphous GeSAg films

Abstract The structural changes of GeAAg films results markedly from the irradiation of electron beam, leading to the change in the optical transmission. For the sample on glass substrate containing a large quantity of Ag, the degree and rate of the change in the transmission increase with increasing Ag-concentration of the film and current density of electron beam, respectively, because the great number of fine metallic Ag particles precipitate on the surface of film. For the sample fixed on metal-glid, on the other hand, the Ag-concentration of the irradiated area decreases markedly.

Formation of amorphous AlCr and AlMn alloy films by rf sputtering

Abstract A new type of amorphous alloy, formed in the limited composition range of about 80–90 at.% Al (AlCr) and 70–90 at.% Al (AlMn) was produced by fr sputtering under Ar atmosphere. The existence of the amorphous phase was confirmed by X-ray diffraction, transmission electron microscopy and differential scanning calorimetry. The formation of the amorphous phase is discussed in association with the intermetallic compounds (CrAl7, Mn4Al11, MnAl6, etc.) having crystallographically complex structure, which have nearly the same composition as the amorphous phase. A weak X-ray scattering halo is observed at the diffraction angle lower than of the strongest halo which characterizes the amorphous structure. The weak scattering halo, which is generated by an X-ray interference effect, is considered to be correlated to the small clusters in which a transition metal atom coordinates several Al atoms. The crystallization temperatures of the amorphous alloys are about 400 and 370°C for AlCr and AlMn samples, respectively.

Crystallization kinetics of electro-deposited amorphous CoP alloys

Abstract The crystallization characteristics of amorphous Co-15.2 at.% P and Co-18.4 at.% P alloys were studied by means of a differential scanning calorimeter (DSC) and a transmission electron microscope (TEM). The analysis of DSC data obtained in the isothermal operation was performed by means of the Johnson-Mehl-Avrami (J-M-A) rate equation. The values of the J-M-A time index, n , for the crystallization of Co-15.2 at.% P and Co-18.4 at.% P alloys were 3.3 ± 0.1 and 2.2±0.1, respectively. It has been revealed through these experimental results and TEM observation during the crystallization process of the amorphous alloys that the crystallization of the former alloy results in interface-controlled three-dimensional spherical growth ( n = 3) of Co 2 P crystal, whereas the crystallization of the latter alloy results in two-dimensional growth ( n = 2) of Co 2 P disks having constant thickness. It has also been found that the apparent activation energy for the crystallization is 195 kJ/mol. and 190 kJ/mol. for Co-15.2 at.% P and Co-18.4 at.% P alloys, respectively.

Anion-selective properties of alkali metal-free lead phosphate glasses containing silver chloride and their application in an ion-selective electrode

Abstract Alkali-free lead phosphate glasses containing silver chloride have been developed for anion responsive sensors. From measurements of the final glass compositions by electron probe microanalysis, it became clear that some of chloride ions in the glass bulk were not volatilized during the glass melting process. Compared with phosphate glasses containing silver oxide, the new glass electrodes containing silver chloride could respond more rapidly, although the response behaviour for anionic species were similar. From the electrode potential vs. time curve for the anionic species, the potential rapidly reached equilibrium when these concentrations varied from 10−5 to 10−2 M. The response times, t95, to thiocyanate of the new glass electrode and the phosphate glass electrode containing silver oxide were 30 and 110 s, respectively. Moreover, the response time required for an initial potential change with a concentration jump of thiocyanate with the new glass electrode was found to be independent of the membrane thickness within about 2 mm and of the measuring temperature between 15 and 40°C. It is concluded that the diffusion process of species such as silver ion in the glass bulk does not take part in the initial part of the response behaviour.

Experimental Evidence for Anion Selective Behavior of Ion Beam Sputtered Film of Alkali Metal‐Free Phosphate Glass Deposited on MOS‐Diode

Selective adsorption of an anionic species on an alkali metal-free lead phosphate glass membrane on a metal oxide semiconductor (MOS) diode was studied using capacitance-voltage curves and electron spectroscopy for chemical analysis (ESCA) measurements. The phosphate glass-coated MOS diode shows a linear relationship between the anion concentration and the relative capacitance change. The oxygen binding energy in the phosphate glass as determined by ESCA spectra shows two types of peaks 23.85 and 26.56 eV. It can be concluded that the anionic species can adsorb referably on the lower surface anionic site and that the anion selective characteristics originate from the MOS diode surface