| Summary: | 碩士 === 國立成功大學 === 光電科學與工程研究所 === 96 === The purpose of this research is to investigate the Bottom-gate-type and enhancement-mode thin film transistors with the Al slightly doped ZnO films as the active channel layers. This research changed the different amount of Al slightly doped ZnO films and the thickness of the Al slightly doped ZnO films and investigated electrical characteristics of the device including IDS-VDS and IDS-VGS, the thermal stability and the optical stability.
The carries passed through the channel layer which were low electric conductivity. Because carries were induced at bottom of the channel layer, the region between source and drain were low electric conductivity. This research were changed the cannel thickness with 100nm, 75nm, 50nm, 25nm and 10nm. The thickness of 25nm is better than the others. The bottom-gate-type TFTs operated in enhancement mode with a field-effect mobility of 32.5 cm2 /V-s, an on-off current ratio of ∼107.
This research changed the different amount of co-sputtered Al slightly doped ZnO films with the Al RF power of 12.5W, 25W and 37.5W. When the Al RF power were 25W and 37.5W at VGS=0, IDS were not turned off and saturation. Especially, IDS was larger with the Al RF power of 37.5W. So the Al RF power of 25W was better than the others.
The TTFT was illuminated with 400nm, 500nm, 600nm and 700nm wavelengths for optical stability. The log10 IDS-VGS curves exhibits that the IDS and photoelectric effect were larger and obvious with the shorter illuminated wavelengths.
The TTFT was measured with 25oC, 50oC, 75oC and 100oC for thermal stability. The IDS-VDS curves exhibits that the resistance of linear region was larger with larger temperature so IDS was littler. The log10 IDS-VGS curves exhibits IDS was larger with larger temperature when VGS was negative.
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