LAUSR

Abstract Electrical properties of carbonised organic xerogel based on resorcinol–formaldehyde (RF), prepared by pyrolysis at 675 °C in nitrogen atmosphere for two hours, were investigated. In this temperature an insulator to semiconductor-like transition occurs. The voltage–current (V–I) characteristics indicate the presence of non-linear conductivity depending on the measurement temperature. The origin of the non-linearity in the electrical conductivity is discussed using different theoretical models. The obtained results reveal that this non-linear conductivity starts above a threshold current, which is illustrated by the presence of negative differential resistance (NDR) region. The properties of the obtained NDR are controlled by the applied current and are attributed to a percolation phenomenon in the carbonised sample. The obtained result is very promising for many applications in power electronic technology specially for the development of some negatronic devices.