Metal Assisted Chemical etching (MACE) is a recently developed anisotropic wet etching method that is capable of producing high aspect ratio semiconductor nanostructures from patterned metal film.
In a well accepted model describing MACE process, the oxidant is preferred to be reduced at the surface of metal catalyst, and holes (h+) are injected from metal catalyst to Si or electrons (e−) are transferred from Si to metal catalyst. Si underneath metal catalyst has the maximum hole concentration, therefore the oxidation and dissolution of Si occur preferentially underneath metal catalyst.
Solar energy conversion efficiency is found to be increased when SiNWs with high aspect ratio are employed in the surface of slar light irradiation.
1 Surface condition
Parameter | Process | Reflectance |
Front Side | ||
Surface condition | Metal Assisted Chemical Etching | Low |
Back Side | ||
Surface condition | Polished or textured | High or low |
2 Material properties
Property | Specification | Inspection Method |
Growth method | directional solidification | XRD |
Crystallinity | polycrystalline | Preferential Etch Techniques（ASTM F47-88） |
Conductivity type | P-type | Napson EC-80TPN P/N |
Dopant | Boron | - |
Oxygen concentration[Oi] | ≦1E+17 at/cm3 | FTIR (ASTM F121-83) |
Carbon concentration[Cs] | ≦1E+18 at/cm3 | FTIR (ASTM F123-91) |
3 Electrical properties
Property | Specification | Inspection Method |
Resistivity | 0.5-2 Ωcm (After anneal) | Wafer inspection system |
MCLT (minority carrier lifetime) | ≧2 μs | Sinton QSSPC |
4 Geometry
Property | Specification | Inspection Method |
Geometry | Square or Rectangle | Wafer inspection system |
Bevel edge shape | Line | Wafer inspection system |
Wafer size (Side length*side length) | 156mm*156mm 157mm*186mm 166mm*166mm | Wafer inspection system |
Angle between adjacent sides | 90±3° | Wafer inspection system |
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