Electrical conduction in porous silicon: temperature dependence

The temperature dependent conduction of electrons in a porous silicon film is theoretically investigated by using the fact that the electrical conduction is closely related to the formation of a continuous network of the conducting Si nanocrytallites. For the first time, an analytical expression for the electrical conductivity of porous silicon has been obtained, which demonstrates that the overall temperature dependence of electrical conductivity cannot be described by a single Arrhenius relationship, and there is a change in the electrical transport mechanism at a critical temperature T-c. The critical temperature T-c and the activation energy are found to be dependent on the mean size of Si nanocrystals as well as their size distribution. The present results are supported by several recent experimental observations. (C) 2000 Elsevier Science Ltd. All rights reserved.