Threshold voltage extraction for organic thin film transistor in linear region using asymmetric metal insulator semiconductor capacitive test structure

摘要

Metal Insulator Semiconductor (MIS) capacitors are commonly used as a test structure for characterization of semiconductor/insulator interface. However, MIS devices do not provide useful information in strong accumulation or inversion mode as the capacitance saturates to a constant value. An MIS capacitor with area asymmetry on the other hand, exhibits a gate voltage dependent capacitance in strong accumulation mode and can be used to obtain additional useful information about the semiconductor/insulator interface. The present work describes the use of asymmetrical metal-insulator-semiconductor device for characterization of the threshold voltage in metal-insulator-organic test structures. Simulation results are presented to show that the threshold voltage extracted from these devices not only matches with that extracted from current-voltage characteristics of organic thin film transistors in the linear region but is also much less sensitive to source contact resistance. The experimental results obtained with pentacene as active semiconductor and poly-vinyl-phenol as the dielectric are also presented to demonstrate the operation and merits of the proposed technique.