Temperature Effects on Photoluminescence Properties of Porous Silicon

摘要

The temperature effects on the photoluminescence(PL) properties of porous silicon(PS) have been observed in the early stage. However, the obtained results are different. Through repeated experiments, some different and useful information are got, which benefits us in that PL properties of porous silicon can be fully made use of. Firstly, samples with porosity of 76% and 49% were chosen to study the exciting temperature effects on the PL spectrum. For the samples with low porosity, the decreasing temperature causes the peak wavelength to be red-shifting and that of the samples with high porosity to present the blue-shifting trend. The light intensity of both reaches the maximum at -10℃. These experimental results can be well explained with the synthesized center PL model based on the quantum confinement model, other than the PL efficiency function σ(λ). Thereafter, PL properties of PS samples fabricated separately under the temperature of -10℃, 0℃, 10℃, 20℃ and 30℃ were studied. The results indicate that with the decrease of the etching temperature, the PL intensity increases from 406.7 to 716.6 and the peak wavelength blue-shifts from 698.9nm to 671.8nm. The WHFM of the PL spectrum dramatically narrows. At the same time, the images observed by AFM show that with the decreasing temperature, the holes are becoming deeper and the porosity is higher, which suggests that the decreasing temperature accelerates the etching rate.