Dear Memsnet members,
I'm looking for theoretical explanation of SiO2 wet etching phenomena in
HF acidand buffered HF in NH4F. It is known that the etching rate of Ge-doped
SiO2 in HF is higher than of pure SiO2 and in the case of ething in bufered HF
the
effect is inverted, i.e. the pure SiO2 is etched faster than Ge-doped SiO2.
I found a couple on papers on this subject but I can't find chemical explanation
enywhere.
Thanks for your help.

Edi