CONDUCTION MECHANISMS IN SILICON-BASED NANOCOMPOSITES

• Published in: Journal of Optoelectronics and Advanced Materials 2004-03, Vol.6 (1), p.53-56
• Main Authors: Iancu, V, Draghici, M, Jdira, L, Ciurea, M L
• Format: Article
• Language: English
• ISSN: 1454-4164

Electrical conduction mechanisms in Si - SiO2 nanocomposite films were experimentally investigated and theoretically modelled. The films with silicon volume concentration varying from 0 % to 100 % were deposited on rectangular quartz substrates. They were prepared by co-sputtering CVD from two targets, one of silicon and one of silicon dioxide. Their middle part is formed by Si nanodots embedded in SiO2. 50 parallel aluminium electrodes were deposited, forming 49 coplanar samples, centred around x = 45 % Si concentration. The microstructure investigations proved that the silicon nanodots have diameters between 4 nm (x = 23 %) and 36 nm (x = 81 %). The current - voltage characteristics were measured at room temperature, in the - 25 4.+ 25 V interval. The obtained curves are symmetric and superlinear. As the current - voltage characteristic is determined by the maximum resistance met by the carriers in their path, the experimental curve is modelled by the field-assisted tunnelling under Coulomb blockade. The used parameters are correlated with previous results obtained on nanocrystalline porous silicon. The correlation coefficient between the theoretical formula and the experimental data is greater than 99.95 %.