Anodic electrode reaction of p-type silicon in 1-ethyl-3-methylimidazolium fluorohydrogenate room-temperature ionic liquid

The anodic electrode behavior for a p-type silicon single crystal electrode ((1 0 0), ρ = 0.01–0.02 Ω cm, boron doped) was examined in the 1-ethyl-3-methylimidazolium fluorohydrogenate, EtMeIm(FH)2.3F, room-temperature ionic liquid (RTIL). The electrochemical behavior was very similar to that in conventional HF aqueous solution. After the anodic electrode reaction, the Si electrode was uniformly covered with a mesoporous Si layer having a pore size of ∼25 nm. The mesoporous layer did not exhibit a photoluminescence spectrum in the visible region due to the lack of Si–H termination. However, after chemical treatment with an ethanolic HF solution, a subset of the porous Si samples showed a very weak photoluminescence.