Fabrication and characterization of porous silicon using electrochemical etching

Abstract

Porous silicon is a unique material that is a network of void space in a silicon matrix. It has attracted particular attention due to the fact that it is silicon based, which facilitates device integration into a standard microelectronics and it is porous, which allows for tuning of its optical properties. In this thesis, we fabricated micro- and macro- porous silicon using electrochemical etching. Microporous silicon whose morphology is sponge-like has been formed in 30mA/cm$^{2}$ constant current density using highly doped p-type (100) silicon wafer. Microporous silicon exhibits strong broad visible(red to orange) photoluminescence at room temperature in accordance with hydrofluoric acid concentrations and constant current densities. Random macroporous silicon whose pores are deep and straight has been formed in 100 ~ 30mA/cm$^{2}$ constant current density using lowly doped p-type (100) silicon wafer. We demonstrated the fabrication of ordered macropore array using standard lithography and the surface activation of silicon pillars.