Setup
Pt electrode
Can substitute for something more common for RE purposes?
5 % HF or 5 % NH4F
Keep 1 - 5 cm between Si and electrode
Procedure
Apply positive voltage to Si
Notes
Heavier doped areas are removed quicker
No oxidizer required (ie light or HNO3)
Good at emphasizing various Si doping
Much safer than wet chemical alternatives
References
http://books.google.com/books?id=9bk3gJeQKBYC&lpg=PA211&ots=7w5HRCwEnF&dq=doping%20etchants&pg=PA211#v=onepage&q=doping%20etchants&f=false