I have fabricated thin films of SiC and observed that the physical properties of the films are quite different from its bulk. The particle size of grown films is in the range of 10-13 nm whereas the Bohr's radius of SiC is 3-5 nm. Hence, I have ruled out the effect of quantum confinement. What may be the other reason?
Hello,
Did you have any specific properties in mind? The reasons for the differences may be property dependent, so I find it hard to generalize.
Properties like hardness for example may be higher in thin films, since the dislocation (defect) density will be lesser if the film is thin enough. The reduction in defect density can also affect a number of other properties, including optical and electronic properties.
Preferred orientation (texture) of grains in a grown film can affect anisotropic properties. For example, we sputter deposited c-axis oriented ZnO thin films in order to maximize the electromechanical coupling coefficient (which depends on piezoelectric coefficient, stiffness factor etc) of our film. We also found that the film stress was affected by the degree of texturing.
Properties affected by grain size (melting point, sintering temperature, hardness etc) will be different between thin films with nano-size grains and bulk material with grains >100nm.
Hope this helps.
- Abhinav
Dear Satyendra,
As we go from bulk to nano then the surface to volume ratio of material becomes high which is the main cause of altering he numerous physical as well as chemical properties. Therefore you can not ruled out the quantum confinement. In gas sensing point of view the high textured thin film is more suitable towards the selectivity of the particular gas in a mixture of several gases. Moreover, high surface area of thin film provide the more active sites for the adsorption of analyte gas molecules.
Thanks.
Structural and micro structural behaviour will be different for thin films compared to bulk. Since quantum confinement is also ruled out; qualitatively put your query to answer.
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