Li-jun He, Li-yan Wang, Wei-Zhong Chen and Xing-zhao Liu Pages 630 - 635 ( 6 )
Background: Thin films produced by the oblique angle deposition (OAD) method are promising nanocolumns’ materials. Their specific properties depend on the self-shadowing effect and formation of columnar grains by OAD. It determines the coating compliance, and consequently its resistance to spallation, as well as its thermal conductivity. The aims of this paper are to introduce readers to discuss how thermal conductivity of thin films varies with inclined angle and temperature.
Methods: Alumina thin films are fabricated by electron-beam evaporation with oblique angle deposition method. The thermal conductivity is measured by the 3ω method. The film thicknesses are measured by cross-sectional scanning electron microscopy.
Results: The thermal conductivity (λf) of alumina thin films is dependent of film thickness at various inclined angles. While the λf of alumina thin films decreases with the increasing inclined angles at various film thicknesses. The λf of alumina thin films increases with the increasing temperature at various inclined angles.
Conclusion: At the various inclined angles, the thermal conductivity of alumina thin films decreases with the increasing porosity. The cross sectional surface of the 1.1 μm thickness alumina thin film deposited at various inclined angles is the cause that the porosity increases with the increasing inclined angles. It increases with the increasing temperature. So the oblique angle deposition method is an effective way to control the thermal conductivity of thin films.
E-beam evaporation, oblique angle deposition method, thermal conductivity.
The School of Optoelectronic Engineering, Chongqing University of Posts and Telecommunications, Chongqing 400065, China.