Thermo-catalytic deposition of silicon nitride - a new method for excellent silicon surface passivation

The deposition of silicon nitride (SiN) films for the surface passivation of crystalline silicon solar cells by thermo-catalytic chemical vapor deposition (cat-CVD), also known as hot-wire CVD, was investigated. A detailed study was performed to assess the useful parameter range. We found that with this new technique very high gas yield and deposition rate can be reached using a very simple deposition source. Excellent surface passivation of p-type silicon could be achieved for the first time using SiN films deposited by cat-CVD. A very strong correlation of the film composition and surface recombination with the gas flow ratio was observed. The films have been applied to the front and back of solar cells to demonstrate their effectiveness. A detailed comparison between cat-CVD and high-quality plasma-deposited films has been performed, in which the films prove very similar.