Abstract
In this article, we have studied electrical conduction of free-standing porous silicon (FPS) and its comparison with porous silicon (PS). P-type unpolished silicon wafers are used for fabrication of the samples. Dimethylformamide (DMF) instead of ethanol, different current density and various anodization times are applied for preparation. Then, SEM images and morphology of the samples considered. Thickness and porosity of the samples are measured by gravimetric method and
confirmed by SEM analysis. Electrical behavior of PS samples has been investigated in ambient air as a function of the temperature in the interval 200 – 300 K. In the next step, after preparation of PS, the porous layer is separated from substrate to get FPS. The dc electrical conduction of FPS filled with a polar dielectric liquid was investigated. The two contact I-V characteristic is determined by metal/PS rectifying interface, whereas, a linear dependence of the current vs. voltage was found for our FPS samples in the presence of polar liquids. Our results showed that with increasing or decreasing dielectric constants of polar liquids, dc conduction of FPS increased or decreased, respectively. The concentration of free holes is increased by condensation of dielectric liquids. A model of the dielectric confinement for charge carriers is applied to explain the dependence of dc conduction of FPS on the dielectric constant of the ambience of the Si nanostructures.
Keywords
Free-standing porous silicon, Electrical conduction, I-V characteristic, Polar liquids, Dielectric confinement.
Citation
R. S. DARIANI, Z. S. HOSSEINI, DC conduction in free-standing porous silicon, Optoelectronics and Advanced Materials - Rapid Communications, 4, 10, October 2010, pp.1526-1530 (2010).
Submitted at: Aug. 21, 2010
Accepted at: Oct. 14, 2010