▁an od ization ▁cell ▁emp lo ys ▁plat in um ▁c ath ode ▁and ▁sil icon ▁wa fer ▁an ode ▁imm ers ed ▁in ▁hydro gen ▁flu or ide ▁( H F ) ▁electro ly te . ▁Rec ently , ▁in ert ▁diam ond ▁c ath odes ▁are ▁used ▁to ▁avoid ▁met all ic ▁imp ur ities ▁in ▁the ▁electro ly te ▁and ▁in ert ▁diam ond ▁an odes ▁form ▁an ▁improved ▁elect rical ▁back ▁plate ▁contact ▁to ▁the ▁sil icon ▁w af ers . ▁Cor ros ion ▁of ▁the ▁an ode ▁is ▁produced ▁by ▁running ▁electric ▁current ▁through ▁the ▁cell . ▁It ▁is ▁noted ▁that ▁the ▁running ▁of ▁constant ▁DC ▁is ▁usually ▁implemented ▁to ▁ensure ▁steady ▁tip - con cent r ation ▁of ▁H F ▁resulting ▁in ▁a ▁more ▁hom ogeneous ▁por os ity ▁layer ▁although ▁p uls ed ▁current ▁is ▁more ▁appropriate ▁for ▁the ▁formation ▁of ▁thick ▁sil icon ▁w af ers ▁bigger ▁than ▁ 5 0   µ m . ▁ ▁It ▁was ▁noted ▁by ▁Hal ima ou i ▁that ▁hydro gen ▁evolution ▁occurs ▁during ▁the ▁formation ▁of ▁por ous ▁sil icon . ▁ ▁When ▁purely ▁a que ous ▁H F ▁solutions ▁are ▁used ▁for ▁the ▁PS ▁formation , ▁the ▁hydro gen ▁b ub bles ▁stick ▁to ▁the ▁surface ▁and ▁indu ce ▁later al ▁and ▁in - depth ▁in hom ogene ity ▁The ▁hydro gen ▁evolution ▁is ▁normally ▁treated ▁with ▁absolute ▁eth an ol ▁in ▁concentration ▁exceed ing ▁ 1 5 %. ▁It ▁was ▁found ▁that ▁the ▁introduction ▁of ▁eth