Recent Progress in Surface and Interface Properties of Nanostructures

The surface of any solid-state object is characterized by enhanced surface energy as compared with the volume of a part of the bulk object [...

The effect of surface treatment in polyacrylic acid solution on the photoluminescent properties of porous silicon

Porous silicon (por-Si) has a unique combination of physicochemical parameters: well-developed surface and hence high sorption. Depending on technology it is possible to form nanometer size pores and clusters in porous silicon which makes this material promising for developments in the field of optoelectronics and sensors. However the high surface activity makes por-Si unstable when exposed to atmosphere. In this work we have studied the effect of por-Si surface treatment in a polyacrylic acid water solution on the composition and photoluminescence (PL) of the material. Por-Si was produced from two fluoric acid solutions. One was a standard solution of fluoric acid, isopropyl alcohol and hydrogen peroxide, and the other was a mixture of fluoric acid and dimethylformamide. We have shown that depending on por-Si technology, its treatment in polyacrylic acid solution allows increasing and stabilizing por-Si PL or changing PL band position and significantly increasing its integral intensity

Features of the Composition and Photoluminescent Properties of Porous Silicon Depending on Its Porosity Index

Porous silicon samples with a porosity index of 5% to 80% were obtained in this work by electrochemical etching, and their photoluminescence properties were also studied. The porosity index was calculated according to the data from X-ray reflectometry. The composition of the surface was controlled by ultra-soft X-ray spectroscopy and infrared (IR) spectroscopy. The degree of the sample surface oxidation increased with the porosity enhancement. Two known mechanisms of photoluminescence in porous silicon were detected that are related to the composition and morphology of its surface. The values of the porosity index specifying the dominations of these mechanisms were determined. Enhancement of photoluminescence was shown to be attributed to an increase in the porosity index