N-type silicon nanowires prepared by silver metal-assisted chemical etching: Fabrication and optical properties

摘要

This paper reports the fabrication of silicon nanowires (SiNWs) by silver (Ag) metal-assisted chemical etching (MACE) method. N-type Si (100) wafers, doped with phosphorus with the resistivity from 1 divided by 10 Omega x cm, were selected for sample preparation. Ag particles of about 30 nm in diameter, which were used as the catalytic metal, were aggregated on the surface of the Si wafer immersed in HF (4.6 M) and AgNO3 solution, with the variation concentration of 15-35 mM, for one minute. Consequently, the Si wafers covered with Ag particles were etched in HF (4.8 M) and H2O2 (0.4 M) solution for the formation of vertically aligned SiNWs. We found that the size and density of SiNWs decreased with the increase of AgNO3 concentration. After a delay time of about 30-40 min, the SiNWs growth depended linearly on the etching time. The light emission from the prepared SiNWs observed at room temperature was well resolved with two bands at around 450 nm (similar to 2.75 eV) and 700 nm (similar to 1.77 eV). The origins of the two emission bands and the comparative aspects are presented and discussed.