Pentacene-based organic thin-film transistors have been fabricated using a phosphonate-linked anthracene self-assembled monolayer as a buffer between the silicon dioxide gate dielectric and the active pentacene channel region. Vast improvements in the subthreshold slope and threshold voltage are observed compared to control devices fabricated without the buffer. Both observations are consistent with a greatly reduced density of charge trapping states at the semiconductor-dielectric interface effected by introduction of the self-assembled monolayer.

Organic thin-film transistors using pentacene as the semiconductor were fabricated on silicon. A series of phosphonate-based self-assembled monolayers (SAMs) was used as a buffer between the silicon dioxide gate dielectric and the active pentacene channel region. Octadecylphosphonate, (quarterthiophene)phosphonate, and (9-anthracene)phosphonate SAMs were examined. Significant improvements in the sub-threshold slope and threshold voltage were observed for each SAM treatment as compared to control devices fabricated without the buffer. These improvements were related to structural motif relationships between the pentacene semiconductor and the SAM constituents. Measured transistor properties were consistent with a reduction in density of charge trapping states at the semiconductor-dielectric interface that was effected by introduction of the self-assembled monolayer.

Groups of thin-film transistors using a zinc tin oxide semiconductor layer have been fabricated via a combinatorial rf sputtering technique. The ZnO : SnO 2 ratio of the film varies as a function of position on the sample, from pure ZnO to SnO 2 , allowing for a study of zinc tin oxide transistor performance as a function of channel stoichiometry. The devices were found to have mobilities ranging from 2 to 12 cm 2 / V s, with two peaks in mobility in devices at ZnO fractions of 0.80± 0.03 and 0.25± 0.05, and on/off ratios as high as 10 7. Transistors composed predominantly of SnO 2 were found to exhibit light sensitivity which affected both the on/off ratios and threshold voltages of these devices.

No abstract