Simultaneous changes in the photoluminescence, infrared absorption and morphology of porous silicon during etching by HF

Abstract

Changes in the photoluminescence (PL), microstructural morphology and the chemical nature of the surface of porous silicon (PS) when it is attacked with a 1:1 mixture of concentrated hydrofluoric acid and water have been studied. As the PS dissolves, the porous structure is essentially destroyed while the appearance and chemical composition of the surface change. At the same time, the intensity and peak wavelength of the PL change dramatically. The simultaneous investigation of PL, FTIR absorption and SEM observation of porous silicon layers (PSL) lend support to the view that chemical passivation, in particular by oxygen, is the major factor which controls the origin of PL. The PL intensity and the PL shift are ascribed to the changes in hydrogen and oxygen termination of pores.