Three approaches to surface substance role investigation in porous siliconphotoluminescence and its excitation

Photoluminescence (PL) and photoluminescence excitation spectra research, a s well as secondary ion mass spectroscopy and infrared vibration spectra me asurements, were used for the investigation of PL excitation mechanism of p orous silicon. It is shown that there are two types of porous silicon PL ex citation spectra: one that consists of visible and ultraviolet bands and on e that contains only an ultraviolet one. The different dependencies of inte nsity of each excitation band upon anodization regimes, as well as ageing a nd thermal treatment, were observed, Two excitation channels have been show n in porous silicon. The visible PL excitation band at 300 K has been attri buted to light absorption of some species on the Si wire surface. The natur e of ultraviolet excitation band is also discussed. (C) 2000 Elsevier Scien ce Ltd. All rights reserved.