実験報告書様式（一般利用課題・成果公開利用）（ ※本報告書は英語で記述してください。ただし、産業利用課題として採択されている方は日本語で記述していただいても結構です。 ）提出日 Date of Report

Experimental Report

2013/02/22

課題番号 Project No.

装置責任者 Name of responsible person

2012A0068

Masayasu Takeda

実験課題名 Title of experiment

装置名 Name of Instrument/（BL No.）

In-situ neutron reflectivity measurements for photodoping ofSHARAKU (BL 17)

silver in Ge-chalcogenide films

実施日時 Date and time of Experiment

実験責任者名 Name of principal investigator2012/05/05-05/07

Yoshifumi Sakaguchi

2012/06/22-06/24

所属 Affiliation

2012/11/08-11/12

CROSS試料、実験方法、利用の結果得られた主なデータ、考察、結論等を、記述して下さい。（適宜、図表添付のこと）
Please report your samples, experimental method and results, discussion and conclusions. Please add figures andtables for better explanation.
1. 試料 Name of sample(s) and chemical formula, or compositions including physical form.
Ge40S60 films
Ag/Ge40S60 films
Ag film

2. 実験方法及び結果 （実験がうまくいかなかった場合、その理由を記述してください。）
Experimental method and results.

If you failed to conduct experiment as planned, please describe reasons.

Experimental method:
In order to clarify the change on the depth profile in Ag/amorphous (a-) Ge chalcogenide films by silver
photo-doping, we have investigated on the neutron reflectivity of Ag/a-Ge40S60 films under a light illumination.
In the experiment, we used a xenon lamp unit (MAX-303, ASAHI SPECTRA) as an excitation light source. The
illumination area on the film was 20mm x 20mm. Neutron reflectivity measurements have been made on BL17(SHARAKU) with unpolarized neutron beam mode. We measured neutron reflectivity of the sample before lightillumination and after reaching the saturation of the silver photo-doping in the Q-region up to 0.08 A-1. The
light was exposed on the film for 90 minutes and neutron reflectivity measurements have also been madeduring the light illumination, fixing the angle of a detector.
Experimental results:
Fig.1 shows the neutron reflectivity of Ag 500	 Å / a-Ge40S60 1500Å / Si substrate (the thicknesses were given
by a quartz crystal unit in a thermal evaporator) before making a light exposure. The dots show theexperimental data while the solid curve shows the result of fitting. The inset table summarizes the thicknesses
which were used in the fitting calculation. As shown in the table, the film is considered to maintain the twolayer structure composed of Ag and a-Ge40S60, without making silver photo-doping.
12. 実験方法及び結果（つづき） Experimental method and results (continued)

Fig.1 (Left) Neutron reflectivity of Ag 500	 Å/a-Ge40S60 1500Å /Si substrate film before making light illumination.
Fig.2 (Right) Neutron reflectivity of Ag 500	 Å/a-Ge40S60 1500Å / Si substrate film after reaching the saturationof silver photo-doping.
Fig.2 shows the neutron reflectivity of the film after reaching the saturation of silver photo-doping. As shownin the table, a pure silver layer has been disappeared while silver-doped Ge40S60 layer has been formed leaving
non-silver-doped Ge40S60 layer (pure Ge40S60 layer) region. This result of fitting shows that silver photo-doping
occurs forming one uniform silver-doped layer, which is distinguished from pure Ge40S60 layer. This isconsistent with previous results of RBS, ESCA and optical measurements, showing that the silver diffusion
front has a step-like concentration profile.

Fig. 3 Time evolution of neutron reflectivity during light illumination

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The time evolution of neutron reflectivity during light illumination is plotted in Fig.3. As shown in the figure, wecould observe the neutron reflectivity in the process of silver photo-doping from an initial state every 10minute. Before making experiments, we have expected to have a clear change in the reflectivity profile,indicating a presence of three layers (Ag/ Ag photo-doped a-Ge40S60 / pure a-Ge40S60) and time evolution oftheir thicknesses. However, we have failed to fit modeled neutron reflectivity profiles to the experimental data,by assuming such three layers. Probably, the process of silver photo-doping cannot be described by the threelayers model and we might need much consideration on the nature of Ag/ Ag photo-doped a-Ge40S60
interface. We are now trying to solve the problem by further analysis.

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