Organic Field-Effect Transistors with Polarizable Gate Insulators
01 February 2002
The nonvolatile transistor memory element is a known device in silicon electronics. It is used as an information storage device and as an element in adaptive, synaptic, and amplifying circuits. In this device, charge storage or polarization between the gate contact and the semiconductor channel imposes an added voltage between the gate and channel, thereby altering the effective channel voltage relative to the voltage nominally applied at the gate contact (the "gate voltage," V sub g). The charge may be stored and/or polarized in domains within the bulk of the dielectric, or at interfaces between the gate contact and channel, as shown schematically in Figure 1. There is growing appreciation of the capability to fabricate various kinds of electronic circuits from organic materials. Applications demanding inexpensive processing and large coverage area are attractive for "organic electronics." Field-effect transistors (FETs) with organic semiconductor channels have been fabricated in arrays to drive electrophoretic display pixels and polymer dispersed liquid crystal-based displays (http://www.research.philips.com/pressmedia/releases/00090la.html). Complementary logic elements and shift registers containing hundreds of organic-based FETs have been produced. The source and drain electrodes of individual FETs have been patterned using microcontact printing to give extraordinary aspect ratios. Device architectures have been developed to minimize deposition and processing steps.