AVS 53rd International Symposium
    Electronic Materials and Processing Thursday Sessions
       Session EM-ThM

Paper EM-ThM5
Organic Thin-Film Transistors with Novel SAM-Modified Dielectrics

Thursday, November 16, 2006, 9:20 am, Room 2001

Session: Organic Electronic Materials and Devices
Presenter: I.G. Hill, Dalhousie University, Canada
Authors: I.G. Hill, Dalhousie University, Canada
M. McDowell, Dalhousie University, Canada
J.E. McDermott, Princeton University
S.L. Bernasek, Princeton University
J. Schwartz, Princeton University
Correspondent: Click to Email
Pentacene organic thin-film transistors (OTFTs) exhibit charge carrier mobilities very similar to their amorphous silicon counterparts. Several impediments remain, however, which hinder their use in consumer electronic devices, including long-term stability and poor sub-threshold performance. While the implications of the former are obvious, those of the latter are subtler. The sub-threshold slope (a measure of the sharpness of the off-to-on transition) and the threshold voltage impact the total voltage swing which must be applied to the device gate to switch between the on and off states, and thus dictate power supply requirements and power dissipation. Pentacene devices utilizing bare silicon dioxide as a gate dielectric exhibit poor sub-threshold slopes (several volts/decade) and, typically, large positive threshold voltages. Both effects can be attributed to a high dielectric/semiconductor interfacial charge trap density. We have investigated the use of phosphonate-linked self-assembled monolayers (SAMs) to modify the electronic structure to the dielectric/pentacene interface. The SAM molecules were chosen to present a surface for pentacene growth which resembled an existing organic semiconductor layer, thus reducing the density of interfacial defects and charge trapping sites. Devices incorporating these SAMs have demonstrated near-zero threshold voltages and sub-threshold slopes less than 200 meV/decade of current, which is only 3x the thermodynamically allowed limit.