Closed space sublimation is a method of producing thin-films, esp.

cadmium telluride photovoltaics Cadmium telluride (CdTe) photovoltaics is a photovoltaic (PV) technology based on the use of cadmium telluride in a thin semiconductor layer designed to absorb and convert sunlight into electricity. Cadmium telluride PV is the only thin film ...

, though it is used for other materials like

antimony triselenide Antimony triselenide is the chemical compound with the formula Sb2 Se3. The material exists as the sulfosalt mineral antimonselite ( IMA symbol: Atm), which crystallizes in an orthorhombic space group. In this compound, antimony has a formal ...

Example of a Close Space Sublimation setup

It is a type of

physical vapor deposition Physical vapor deposition (PVD), sometimes called physical vapor transport (PVT), describes a variety of vacuum deposition methods which can be used to produce thin films and coatings on substrates including metals, ceramics, glass, and poly ...

where the substrate to be coated and the source material are held close to one another. They are both placed in a vacuum chamber, which is pumped down. The source and substrate are then heated. The source is heated to some fraction of its melting temperature, and the substrate some lower temperature e.g. 640 °C and 600 °C, respectively. This causes sublimation of the source, allowing vapors to travel a short distance to the substrate, where they condense, producing a thin film. This short-path diffusion is similar in principle to short-path distillation. Compared to other techniques, it is a relevantly insensitive process, and takes as little as 15 minutes for an entire cycle. This makes it a very viable technique for large-scale manufacturing.

References

{{reflist, refs= {{cite web , last=Potamialis , first=C. , last2=Lisco , first2=F. , url=https://www.cdt-pv.org/media/upload/Christos_Potamialis_PVSAtPoster.pdf , title=Fabrication of CdTe Thin Films by Close Space Sublimation , website=Centre for Doctoral Training New and Sustainable Photovolatics , publisher=Centre for Renewable Energy Systems Technology (CREST), Wolfson School, Loughborough University , access-date=26 April 2019 {{cite journal , last1=Birkett , first1=Max , last2=Linhart , first2=Wojciech , last3=Stoner, first3=Jessica , last4=Phillips, first4=Laurie , date=24 May 2018 , title=Band gap temperature-dependence of close-space sublimation grown Sb2Se3 by photo-reflectance , journal=APL Materials , volume=6 , issue=8 , pages=084901 , doi=10.1063/1.5027157 , doi-access=free Thin film deposition Semiconductor device fabrication