Porous Si (111) Fabrication Using Electrochemical Anodization: Effects of Electrode Distance and Current Density

Porous silicon (PSi) has developed for many applications such as gas and humidity sensors. Various methods are available to fabricate PSi, electrochemical anodization is common due low cost easy use. Current density, etching/anodization time, type of etching solution, electrode distance the parameters determining resulting pores. The substrate used n-type wafer with (111)-orientation resistivity 1.5-4.5 Ω.cm a size 1.5×1 cm2. cleaning process samples employed RCA procedure. Conductive contacts required were aluminum on samples. electrodes Si sample acting anode platinum (Pt) cathode. solution using mixture HF (40%) ethanol (99%) 1:1 ratio. was 1.5, 2.0, 2.5 cm. current density each 10, 30, 50 mA/cm2 an time 30 min. SEM UV-Vis characterizations applied obtain surface morphology reflectance, respectively. For all samples, reflectance PSi lower than original (no pores). This condition indicates that suitable anti-reflective layer in solar cell. However, curves irregular shapes function wavelength different density. images confirmed pores formed inhomogeneous. pore decreased increase while it increased There correlation between at specific numbers.