Visible Luminescence from Porous Silicon

Abstract

The visible photoluminescence (PL) at room temperature from electrochemically etched Si has attracted much attention as it opens up new possibilities for Si as a material for optoelectronic applications. The origin of this interesting and potentially important effect is not well understood [ '1-6]. We measured photoluminescence spectra of porous Si layers as a function of temperature between 30 K and 330 K [7]. The PL was excited with 366 nm light from high pressure mercury lamp (200 W). The PL signal was detected with Hamamatsu-375R photomultiplier. The porous silicon layers were prepared by electrochemical etching of the 15 μm thick p-type epitaxial layer (p = 10 Ω cm), deposited on low resistivity (p = 0.01 Ω cm) p+ boron doped (111) silicon substrate. The anodization was performed in the electrolyte containing hydrofluoric acid, water, and isopropyl alcohol. The HF concentration in the electrolyte was changed from 10% to 45% [7]. High reproducibility of the properties of the porous silicon layers was obtained due to good control of proper parameters of its technology. The thickness of the porous layer increases linearly with the time of anodization