Graphene Oxide as a Dielectric and Charge Trap Element in Pentacene-Based Organic Thin-Film Transistors for Nonvolatile Memory

Abstract

In this report, the dielectric nature of graphene oxide (GO) was exploited for the successful implementation of low-power pentacene thin-film transistors suitable for nonvolatile memory applications. Two different types of devices were fabricated on indium tin oxide-coated glass substrates with two different metals, viz., gold and aluminum, as the source and drain contacts. The performance of the devices was analyzed from their field-effect characteristics. Both the devices showed dominant p-type charge transport behavior. The breakdown electric field was determined to be 1.02 × 10⁸ V/m. The current transport mechanism was explained from the output characteristics using the Fowler-Nordheim tunneling theory. Capacitance-voltage (<i>C</i>-<i>V</i>) measurements have been employed to determine the value of the oxide capacitance and to examine the memory effect. The hysteresis behavior observed from the <i>C</i>-<i>V</i> characteristics show the suitability of the device for memory applications with a low operating voltage of 3 V. The charge trapping behavior of GO was explained by the energy band diagram. Frequency-dependent <i>C</i>-<i>V</i> measurements in the range 100 kHz to 1 MHz were also performed to account for the memory window obtained in the devices. The charge retention and endurance characteristics were evaluated under a constant voltage stress to check the reliability of device operation.