Measurement of the dc resistance of semiconductor thin film-gas systems: Comparison to several transport models

摘要

Measurements have been made of the dc resistance of a thin film semiconductor, an indium tin oxide that has been exposed to various gases (acetylene, methane, and sulfur dioxide). The resistance versus time is found to be a characteristic that serves as a possible means for detecting and identifying a gas. Three simple dc transport models are used to determine the time-dependent resistance: resistor network, dynamic Maxwell-Garnett Theory (DMGT), and a dynamic effective medium approximation (DEMA) model. The resistor network model gives only the general trend of the experimental data. The DEMA and DMGT predictions are nearly identical and independent of dimensionality. This promising application of the historic EMA and MGT models yields results that are in good agreement with experimental resistance data presented in this paper. Future directions might include an extension of these dc resistance results to the finite frequency ac and optical conductivity.