Surface electrical conductivity of poly(methyl methacrylate) thin films: Observation of conductivity switching

We present here the experimental results of surface electrical conductivity/current of poly (methyl methacrylate) [PMMA] thin films prepared from chloroform solvent. The switching in current/conductivity in PMMA thin films at a certain bias voltage (threshold voltage) has been observed from the current-voltage characteristics under certain experimental conditions. Such switching in current has been observed to depend on the sample cell temperature and illumination of light. Interestingly the conductivity switching was not noticed at room temperature for the measurements under dark conditions. The mechanisms for the electrical conduction in the two voltage regions, i.e. the voltage regions lower and higher than the threshold voltage are different. The results have been interpreted on the basis of creation of conduction paths at a certain bias voltage due to the structural reorganization/reorientation in PMMA matrix. (C) 2011 Elsevier B.V. All rights reserved.