Research Center for Solar Energy Chemistry, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan.
ACS Appl Mater Interfaces. 2013 Feb;5(4):1262-8. doi: 10.1021/am302314y. Epub 2013 Feb 6.
By bringing an anodically biased needle electrode into contact with n-type Si at its tip in a solution containing hydrofluoric acid, Si is etched at the interface with the needle electrode and a pore is formed. However, in the case of p-type Si, although pores can be formed, Si is likely to be corroded and covered with a microporous Si layer. This is due to injection of holes from the needle electrode into the bulk of p-type Si, which shifts its potential to a level more positive than the potential needed for corrosion and formation of a microporous Si layer. However, by applying square-wave potential pulses to a Pt needle electrode, these undesirable changes are prevented because holes injected into the bulk of Si during the period of anodic potential are annihilated with electrons injected into Si during the period of cathodic potential. Even under such conditions, holes supplied to the place near the Si/metal interface are used for etching p-type Si, leading to formation of a pore at the place where the Pt needle electrode was in contact.
通过将带正偏压的针状电极与尖端的 n 型 Si 在含有氢氟酸的溶液中接触，在针状电极与 Si 的界面处进行蚀刻，从而形成孔。然而，对于 p 型 Si，尽管可以形成孔，但 Si 可能会被腐蚀并覆盖有微孔 Si 层。这是因为从针状电极注入 p 型 Si 体的空穴会将其电势推向比腐蚀和形成微孔 Si 层所需的电势更正的水平。然而，通过向 Pt 针状电极施加方波电位脉冲，可以防止这些不良变化，因为在阳极电位期间注入 Si 体的空穴会与在阴极电位期间注入 Si 的电子湮灭。即使在这种情况下，供应到 Si/金属界面附近的空穴也会用于蚀刻 p 型 Si，从而在 Pt 针状电极接触的位置形成一个孔。
