| Budget Amount *help |
¥1,900,000 (Direct Cost: ¥1,900,000)
Fiscal Year 1994: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1993: ¥1,500,000 (Direct Cost: ¥1,500,000)
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| Research Abstract |
With the high-spatial resolution (-nm) of transmission electron microscopes(TEM), a measurement method of thermal conductivity of thin films is investigated and it is applied to polycrystalline films whose thickness is 30-300nm.
Electrons through a film are scattered by the thermal vibration of lattice and the beam intensity at TEM image changes by the temperature of the specimen. When the laser beam is focused on a film, the film can be heated locally, quickly and repeatedly. combining these functions, we can investigate the mechanize of heat transfer in this films.
A He-Ne gas laser with amplitude modulator and an optical system for focusing and aligning are attached to the TEM.The laser beam with about 10mW is focused on the specimen to the area of 10-20mum in diameter. The magnified image of the specimen is observed and the beam intensity in a small area (1mumphi on specimen) is detected by a scintillator and a photo-multiplier.
The rise of film temperature is delayd to the laser power by the heat capacity and heat diffusivity. The phase difference is converted to the thermal conductivity. Then, this method has advantage that the deduction is independent to the absolute temperature and the film thickness.
Some vacuum-deposited films (Al, Sn, Ni, Ge, Cu, Mg, Bi) with various thicknesses are prepared and measured. In most cases, film conductivity is in 30-80% of bulk conductivity and approaches to it as the grain size increases. The film conductivity reduces as the thickness decreases.
In the term of project, we have not finished the investigation to the relation between heat transfer and crystal structure. This will be studied in succession.
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