Solar Wafer
Silicon wafer 125 mono
| Property | Specification |
| Crystal and material properties | |
| Crystallinity | Monocrystalline |
| Conductivity type | P-type |
| Boron | Boron |
| Specific resistance | 1.0 - 3.0 Wcm; 90% within 1-1.8 ohm-cm |
| Crystal size | ≤ 10 crystals per cm² |
| Oxygen concentration | ≤ 9.7 x 1017 atoms/cm³ |
| Carbon concentration | ≤ 5 x 1016 atoms/cm³ |
| Effective minority carrier lifetime |
1: ≥ 1 µs 2: Average > 3.5 µs 3: No lifetime dip > 3 µs |
| Geometry | |
| Shape | Square with 45±10° chamfer at the corner |
| Length of wafer edge | 125 +/- 0,5 mm Cpk ≥ 1.33 |
| Minimum square area covered | Min (d-0.5 mm)x(d-0.5 mm), Max (d+0.5 mm)x(d+0.5 mm) |
| Square area, outside of which no part of the wafer can extend |
|
| Bevel edge width | 1.5 ± 0.5 mm |
| Average thickness | 200 ± 20 µm with Cpk ≥ 1.33 |
| Total thickness variation TTV | ≤ 50 µm with Cpk ≥ 1.33 |
| Warp/Bow | ≤ 40 µm with Cpk ≥ 1.33 |
| Appearance | |
| Edge defect (through wafer) | ≤ 1 mm with ≤ 0.5 mm |
| Surface chipping | None above 0.2 mm wide and 0.2 mm deep |
| Saw marks | depth ≤ 20 µm |
| Saw marks (steps) | depth ≤ 15 µm |
| Cracks and pin holes | No visual cracks and pin holes |
| Surface properties | |
| Wafer slicing | Glycol based wafering |
| Wafer cleaning | Water + detergent |
| Wafer surface | As cut, no stains with the exception of water stains and stains of silicon dust |
| Packaging | |
| Packaging method | Cardboard boxes packed in cardboard cartons |
| Labelling on each | Date / Time, Ingot number, |
| cardboard boxes | Box number, Number of wafers, Thickness |
| Labelling on each | Carton Number, Wafer |
| cardboard cartons | description, Article number Number of wafers, Date |
The solar wafer is cut from the solar ingot. Large silicon solar ingots are sliced into very thin solar wafers, which are then processed into solar cells. A solar cell is also called photovoltaic cell or photoelectric cell as it uses the photovoltaic effect to convert the energy of light directly into electricity
Many currently available solar cells are made from bulk materials that are cut into wafers between 180 to 240 micrometers thick that are then processed like other semiconductors.
A solar ingot is a chunk or oblong block of silicon. The most prevalent bulk material for solar cells is crystalline silicon also known as solar grade silicon.
Other materials currently used to make photovoltaic solar cells other than mono-crystalline silicon include polycrystalline silicon, amorphous silicon, cadmium telluride and copper indium selnide/sulfide.
There are different sawing machines available that is used to slice the crystalline silicon ingot into solar wafers for making solar cells. These machines saw the silicon solar ingot at a specific thickness ranges for example 180 micrometer.
