Experimental and modeling study of the capacitance-voltage characteristics of metal-insulator-semiconductor capacitor based on pentacene/parylene

The capacitance-voltage (C-V) characteristics of metal-insulator-semiconductor (MIS) capacitors consisting of pentacene as an organic semiconductor and parylene as the dielectric have been investigated by experimental, analytical, and numerical analysis. The device simulation was performed using two-dimensional drift-diffusion methods taking into account the Poole-Frenkel field-dependent mobility. Pentacene bulk defect states and fixed charge density at the semiconductor/insulator interface were incorporated into the simulation. The analysis examined pentacene/parylene interface characteristics for various parylene thicknesses. For each thickness, the corresponding flat band voltage extracted from the C-V plot of the MIS structure was more negative than -2.4 V. From the flat band voltage the existence of a significant mismatch between the work functions of the gate electrode and pentacene active material has been identified. Experimental and simulation results suggest the existence of interface charge density on the order of 3 x 10(11) q/cm(2) at the insulator/semiconductor interface. The frequency dispersion characteristics of the device are also presented and discussed. (c) 2011 Elsevier B.V. All rights reserved.