It is the purpose of this experiment to study how the growth of evaporated BaTiO3
deposit in vacuum into crystal films varies dependening on the difference between the degree of vacuum and the deposition rate.
The degrees of vacuum applied were from 2×10-3
Torr. A tungsten boat filament was used for evaporation heater. The deposition rates were varied from 1 to 30Å/s by changing the current intensity applied to the filament. The thickness of the films was 1μm to 2.5μm.
The substrate used was a platinum plate and its temperature was kept at 500°C constant.
As the result the condition of the films is found as follows as they have been examined by X-ray diffractions:
In the cases of 10-3
Torr only the diffraction lines of the platinum plates are observed, but almost no trace is observed of crystal of BaTiO3
, regardless of deposition rates, while in the cases of 10-5
Torr, when the deposition rates are relatively smaller strong diffraction lines of BaTiO3
However the electron micrographs show that as the deposition rate increases the corresponding sizes of the crystals become larger until the rate reaches 10Å/s. At this peak, the size begins gradually to be smaller as the rate increases.
These crystals are all of cubic system.
Impurities of BaWO4
are present in all the samples irrespective of the degree of vacuum and the diposition rate.