Silver nanoparticle-induced interface dipole and energy band bending in graphene quantum dot/pentacene FETs: memory window compromise and current modulation

초록

The introduction of graphene quantum dots (GQDs) in a pentacene field effect transistor (FET) device structure notably improved the on/off ratio, demonstrating a significant memory window. This indicates that GQDs are effective in enhancing carrier retention properties. However, the subsequent introduction of Ag nanoparticles (NPs) between the pentacene layer and GQDs led to a significant decrease in the memory window and a far smaller on/off ratio. This decrease is primarily attributed to an increase in the "off" current, suggesting a detrimental impact of Ag NPs on the device performance. The formation of an interface dipole at the Ag NPs-GQDs interface appears to be the main factor behind this effect, influencing the energy band bending and altering the flat band energy. The integration of Ag NPs into the device not only modifies the threshold voltage and elevates the "off" current through interface dipole effects, but also considerably diminishes the "on" current. This reduction is attributed to the dual influences of reduced carrier concentration resulting from screening phenomena and the obstruction of charge movement caused by interfacial scattering. This twofold effect on both the "on" and "off" currents underscores the complex influence of Ag NPs in regulating the electronic behavior of the FET device.

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