Analysis of optical and thermal properties of thermally oxidized mesoporous silicon layers

• Porous silicon was manufactured by the conventional electrochemical anodization.
• Effect of annealing on optical and thermal properties was investigated.
• Thermal conductivity and diffusivity increased with thermal treatments.
• Reflectance of the samples decreased with thermal treatments.
• All samples exhibit a photoluminescence peak position centered on 2.1 eV.

In this paper we will report the evolution of optical and thermal properties of thermally oxidized mesoporous silicon layers. The samples were manufactured by the conventional electrochemical anodization. The modification process including thermally oxidized samples in dry oxygen at different temperatures and duration was conducted. After treatment, the products were characterized by Spectral Reflectance in the wavelength range of 200–1100 nm which served to exclude an important decrease of the optical loss with temperature and duration of oxidation. We noticed that thermal oxidation improved the absorption of the UV light and led to a significant decrease of the average reflectivity. The band gap energy was performed by the Photoluminescence spectroscopy under an excitation at 325 nm and showed a broad emission centered at around 2.1 eV for all the samples. Furthermore, thermal conductivity and thermal diffusivity were determined by Photothermal Deflection Technique by comparing the experimental curves of normalized amplitude and phase of the photothermal signal to the corresponding theoretical ones. It was also found that the increase of both temperature and time of the thermal oxidation process affect the thermal properties of these layers.

Normalized experimental reflectivity of the thermally oxidized porous silicon films.Figure optionsDownload as PowerPoint slide