| Budget Amount *help |
¥6,800,000 (Direct Cost: ¥6,800,000)
Fiscal Year 1998: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1997: ¥2,200,000 (Direct Cost: ¥2,200,000)
Fiscal Year 1996: ¥3,900,000 (Direct Cost: ¥3,900,000)
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| Research Abstract |
The purpose of this project is to clarify the effects of epitaxial growth conditions such as substrate temperature and ambient gas on substrate surface. The contact angle of liquid metal on the surface in ultra-high vacuum (UHV) are measured to study the wetting tension.
1. The contact angle can be measured at the substrate temperature from 20 to 550 degree C in UHV and in hydrogen.
2. We developed a new mechanics to contact Ga droplet and GaAs substrate. We did not drop Ga on GaAs, but GaAs was brought into contact with Ga droplet. This makes easy to remove surface oxide of Ga droplet and possible to measure at more than two temperatures at one evacuation cycle though we use one Ga droplet for one measurement.
3. The contact angle of pure water-treated GaAs surface, oxidized by the water, showed 140 degree constant, though the substrate temperature increased from 20 to 550 degree C in UHV.
4. The contact angles of cleaned GaAs in semicoclean solution and/or low dissolved oxygen pure water-treated GaAs, which surface oxide were reduced, decreased from 140 to 120 degree, as the temperature increased in UHV.
5. The contact angle of cleaned GaAs surface in semicoclean decreased from 130 to 90 degree, as the temperature increased in hydrogen.
6. It was clarified experimentally that wetting tension of GaAs substrate, which showed the grade of wetting, influence on the electrical characterization of epitaxially grown Ge films on the GaAs.
7. It is better to use GaAs treated with semicoclean etc., and to grow in hydrogen for low temperature epitaxial growth of Ge on GaAs.
Contact angle measurement in UHV is one of the promising technique to investigate the best growth condition for low temperature epitaxy.
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