| Summary: | 碩士 === 國立彰化師範大學 === 光電科技研究所 === 103 === In the research, variety of pentacene based transistors with polymer insulator (PMMA)were investigated. The first part of the experiment carried out the electrical measurement and comparison of pentacene organic thin film transistors. The result shows that transistors have larger drain current for shorter channel devices than the others. And all the devices show good stabilities, thus we could doping Na and K for the further investigation.
In the petacene doped with potassium elements experiments, we got the on / off current ratio (On / Off current ratio) increased, sub-threshold slope (SS) decreased, threshold voltage (VTH) upward, and carrier mobility (μSat) shows a downward trend. The threshold voltage VTH consistent conversion curve shift to negative voltage direction because the potassium elements doped into semiconductor layer will increase the positive ion counts, in order to balance the impact, the gate need to increase the negative bias to offset it. For further conformation, we also performed the sodium doped pentacene same as the organic thin film transistor, also get the same result.
The pentacene-doped potassium or sodium physical properties were measured by XRD, and AFM, in order to observe the properties change and further explain electrical measurement results.
The fourth part of the experiment, we observed the heating temperature and heating time impact on device characteristics for further study.
We can adjust the variable threshold voltage VTH, increasing the range of modulation VTH, with pentacene semiconductor layer doped with potassium or sodium-price elements. And the on / off current ratio (On / Off current ratio) becomes larger, let us greater operating range, but carrier mobility (μSat) became smaller and the heating stability characteristics still need to be improved in the future.
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