vices the required Q S to obtain a specific m is slightly lower than in SiO 2 -and BZT-based devices assuming that there is a reduced concentration of traps in the pentacene channel of solution-processed BST-based TFTs relative to ones comprising BZT or SiO 2 gate insulators.
The use of solution-processed BST films as the high e gate insulator in pentacene IGFETs, required annealing at 400 C. Hence, despite their excellent low voltage device characteristics and performance they are not compatible with transparent plastic substrates, in contrast to the sputtered mixed metal oxide BZT insulators reported in the literature, [8] which were deposited at room temperature. However, given their performance, which is very close to that of the widely used a-Si:H TFT, pentacene IGFETs comprising sol-gel deposited BST films could be good candidates for applications involving AMLCDs or AMOLEDs on glass substrates. The low operating voltage required to produce such performance and the very low subthreshold slope of pentacene/BST-based IGFETs make them very attractive for applications. Furthermore, due to the solutionbased deposition process used, such IGFETs can potentially reduce manufacturing costs, especially if other layers of the device are also deposited from solution. This can prove very important in the future, as cost is expected to become an increasingly important factor in the flat panel display industry.
In conclusion, based on our understanding of the origins of the gate bias dependence of mobility in pentacene IGFETs, [8] we have designed and fabricated high-performance devices, comprising pentacene and a solution-processed, relatively high e BST gate insulator, that require operating voltages up to only 5 V.