Improving the Performance of Organic Thin-film Transistors by Using Gas-doped Pentacene as the Active Layer
| Autor: | Kuo-Lin Chiu, 邱國淋 |
|---|---|
| Rok vydání: | 2013 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 101 Gas-doped pentacene is used as the active layer to fabricate organic thin-film transistors (OTFTs) and their electrical characteristics are discussed. Doping gases are N2 and CH4. The control device is also prepared when the pentacene is evaporated without a gas doping. Comparing with the control device, the OTFTs with the pentacene having CH4 doping of 20 sccm show that the output current (IDS) increases from -2.0 μA to -21.9 μA, the field-effect mobility (μ) increases from 0.12 cm2/Vs to 0.41 cm2/Vs, the on/off current ratio (ION/OFF) increases from 3.7×104 to 5.1×105, and the threshold voltage (VT) decreases from -23.1 V to -10.9 V. Experimental results demonstrate the IDS and μ improved significantly about 10 and 4 times, respectively. X-ray diffraction (XRD) analysis show the pentacene doped by 20 sccm CH4 exhibited better crystallinity than without gas doping. Atomic force microscope (AFM) images show that grain size of pentacene increases and becomes uniform. The grain clusters present a dendritic form, which indicates the pentacene has well-interconnected grains. Therefore, less grain boundaries cause the reduction of the interface trap density (Dit) between the dielectric layer and the active layer, thus enhance the electrical characteristics of OTFTs. At the metal/organic interface, the interfacial dipole might be a major factor to affect charge transport. The interfaces of Ag/undoped pentacene and Ag/gas-doped pentacene have been investigated using ultrat-violet photoelectron spectroscopy (UPS). The difference between the Fermi Level of anode and the HOMO of 20 sccm CH4-doped pentacene is effectively reduced, then enhancing carriers injection into the active layer from anode. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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