High Purity Porous Silicon
Porous Silicon powders come in two varieties. The first variety are very pure >99.99% Si particles that have been electrochemically etched using HF and a solvent.
The second variety, similar in function to the electrochemically etched pure Si, but has been optimized to be cost effective. By using metallurgic Si, with a purity of roughly 91% Si, and an electroless chemical etching process the Price per gram can be drastically reduced.
Typical particle sizes range from 20-150µm. Depending on volume, etching parameters and application requirements the particles can also be reduced in the sub-micron and nanoparticle regimes.
Typical porosity ranges are between 40% and 75% for electrochemical etching and upto 50% for electroless etching
For customized material, tests can be done to find the correct balance between pore diameter and overall porostiy.
Porous Silicon Wafer Etching
Starting with 6″ <1-0-0> Cz p-type Si Wafers >300µm thickness:
Micro-, Meso- and Macroporous Silicon can be etched to a certain thickness, pore size and porosity. Categories are divided below.
- Microporous Etching
( 1-5nm Pore Diameters)
- Mesoporous Etching
( 5-50nm Pore Diamters)
- Macroporous Etching
( >50nm Trenches or Vias)