Week 11: Thin film deposition techniques & Epitaxial films growth modes
Chapter 3 Thin film deposition techniques: Thin film deposition is a process applied in the semiconductor industry to grow electronic materials, in the aerospace industry to form thermal and chemical barrier coatings to protect surfaces against corrosive environments, in optics to impart the desired reflective and transmissive properties to a substrate and elsewhere in industry to modify surfaces to have a variety of desired properties.
The deposition process can be broadly classified into:
- Physical vapor deposition (PVD)
- Chemical vapor deposition (CVD)
In CVD, the film growth takes place at high temperatures, leading to the formation of corrosive gaseous products, and it may leave impurities in the film. The PVD process can be carried out at lower deposition temperatures and without corrosive products, but deposition rates are typically lower.
Epitaxy & Epitaxial thin film growth modes: The growth of epitaxial thin films is determined by the balance of the different surface free energies involved and follows one of the three well-known mechanisms:
Frank-van der Merwe mode (Layer by Layer or very smooth growth)
Volmer-Weber mode (Island or very rough growth)
Stranski-Krastanov mode (Layer by layer plus island growth)