Photovoltaic graphite substrate process flow

How are photovoltaic silicon ingots grown?

Photovoltaic silicon ingots can be grown by different processes depending on the target solar cells: for monocrystalline silicon-based solar cells, the preferred choice is the Czochralski (Cz) process, while for multicrystalline silicon-based solar cells directional solidification (DS) is preferred.

Why is graphite used in photovoltaic Si processing?

Graphite can satisfy this requirement in view of its high mechanical performances at elevated temperatures. Additionally, graphite is a low-cost material and its corrosion in the neutral gas atmospheres used in photovoltaic Si processing is negligible.

How to Dewett a graphite substrate?

The best de-wetting conditions are achieved by coating the graphite substrates with a two-layer method: (i) the first layer is a porous Si 3 N 4 or Si 3 N 4: SiC layer to suppress SiO 2 -graphite interaction, (ii) the second layer is Si 3 N 4 mixed with colloidal silica to improve the surface non-wetting properties.

Do coating configurations prevent silicon infiltration into graphite substrates?

A thorough investigation is needed for the possible interactions at (i) the graphite-coating interface and (ii) the coating-liquid silicon interface of all proposed coating methods. In this work, we suggest different coating configurations that act as barrier layers and prevent silicon infiltration into graphite substrates.

Do graphite-silicon substrates wettable?

Most of the previous studies [, , , , ] on the graphite-silicon system have examined the wettability and the infiltration of silicon on bare (uncoated) graphite substrates. They have reported a rapid and complete wetting of the substrates followed by a formation of SiC as an intermediate layer.

How is silicon crystallized for photovoltaic applications?

The crystallization of multicrystalline and mono-like silicon for photovoltaic applications is currently performed by directional solidification in amorphous silica crucibles [ 1 ]. Direct contact between molten silicon and silica leads to sticking and to the formation of numerous defects (dislocations, micro-cracks) and even of macro-cracks [ 2 ].