Influence of Reactive Ion Etching Time on Fabrication of Porous Silicon on Si (110) Substrates

Abstract

Porous silicon (PSi) has been fabricated by photolithography and Reactive Ion Etching (RIE) with various etching times in the previous study. The PSi surfaces have the pore size in the range of 12.6-28.0 nm for PSi (111) and 17.4-37.7 nm for PSi (100). Meanwhile, the PSi has the resistivity around (1.14-2.60)×10−4 Ω.cm for PSi (111) and (3.85-9.03)×10−4 Ω.cm for PSi (100). In this study, N-type Si (110) substrate was used to form PSi with various etching times for 10, 20 and 40 min. The PSi samples were characterized by SEM, Dektak XT profilometer, UV-Vis and FPP equipment. PSi formed into a spherical shape which distributed throughout the Si surface. Pore sizes, pore depths and resistivity of patterned PSi increased as the etching time increases, i.e., 4.04 µm, 30.85 nm and 2.26×10−4 Ω.cm (10 min); 4.98 µm, 51.93 nm and 3.86×10−4 Ω.cm (20 min); 6.00 µm, 80.67 nm and 5.77×10−4 Ω.cm (40 min), respectively. This indicated that the pores could be considered as defects or dislocation inside material which resist electrons diffuse toward the electrode. Moreover, the PSi reflectance value decreases 30% to around 10% on the visible light range with the increasing of etching time.