本論文之主要目的是探討石墨烯量子點加入聚甲基丙烯酸甲酯做為浮動閘(載子捕捉層)後對薄膜電晶體操作特性影響之研究。本論文著重在針對有無添加石墨烯量子點的情況下，去做一連串的物性及電性分析，最後再進行可靠度的測試。
實驗分為三個部分，主要比較使用不同材料的浮動閘做為有機薄膜電晶體記憶元件之特性差異。實驗一，先是以聚甲基丙烯酸甲酯做為浮動閘的材料，其結構為n^+型矽(閘極)/二氧化矽(介電層)/聚甲基丙烯酸甲酯(浮動閘)/並五苯(通道層)/金(源極和汲極)。從轉移特性曲線中，可以得知臨界電壓為-20.46V，開關電流比為9.02×104，次臨界斜率為2.37 V/decade，記憶儲存窗為8.52 V。而在實驗二，其結構與實驗一相同，只是改以石墨烯量子點與聚甲基丙烯酸甲酯混合層做為浮動閘的材料。石墨烯量子點在元件中是扮演抓取載子的重要角色，從電特性的量測結果中可明顯看出，混入石墨烯量子點後其開關電流比約提高2倍、次臨界擺幅約降低2倍且記憶儲存窗約提高11倍。而在寫入-讀取-抹除-讀取測試中，具有良好的開關特性，其開/關汲極電流比可以高達104。此外，根據retention time結果，我們發現混入石墨烯量子點後能有效提升載子保存能力。總結以上結果可知混入石墨烯量子點後特性能明顯改善。
最後實驗三，是以實驗二的結構為基礎，在浮動閘上面再多加一層聚甲基丙烯酸甲酯做為穿隧層。原本我們期望多加一層聚甲基丙烯酸甲酯後，能降低表面的粗糙度，使與通道層的接面品質變更好，但從結果顯示，並沒有因此提升電特性及開關特性，且記憶儲存窗反而變更小。我們將這結果歸因於聚甲基丙烯酸甲酯-石墨烯量子點與聚甲基丙烯酸甲酯混合層之間的接面品質不好以及聚甲基丙烯酸甲酯-石墨烯量子點與聚甲基丙烯酸甲酯混合層-二氧化矽三層的總厚度太厚，導致閘極控制能力下降，特性變差。

The main purpose of this thesis is to investigate the impact on thin film transistor’s operation properties after graphene quantum dots (GQDs) blend into poly (methyl methacrylate) (PMMA) as floating gate. This study focused on discussing the condition of adding GQDs or not, and then did a series of physical and electrical analyses. At the end, I did the further reliability testing.
Here we divided the experiment into three parts. The purpose was to do the comparisons of pentacene-based OTFT memory using different materials as floating gate. In experiment I, we used PMMA as floating gate. The structure was composed by n^+-Si (gate electrode) / SiO2 (dielectric layer) / PMMA (floating gate) / pentacene (channel layer) / Au (source and drain electrodes). The threshold voltage of -20.46 V, on/off current ratio of 9.02×104, sub-threshold swing of 2.37 V/decade, and memory window of 8.52 V can be obtained from transfer characteristics. In experiment II, the structure was the same as experiment I, but the floating gate material was changed as PMMA:GQDs composite layer. The GQDs play an important role to capture the carrier charges in the transistor device. From the results of electrical measurement, we could find that it achieved about two times higher on/off current ratio, two times faster sub-threshold swing and eleven times larger memory window after adding GQDs into the PMMA layer. Moreover, in write-read-erase-read cycle test, it had well switching cycle performance. The curves revealed that the probe current of the on-state was four orders of magnitude higher than that of the off-state. Besides, according to the retention time, we found that it could promote the charge storage time after adding in GQDs. All of the results illustrated that it could improve the memory properties by adding GQDs into the PMMA layer.
In experiment III, we used the experiment II’s structure as based, and added the PMMA on the top of PMMA:GQDs composite layer as tunneling layer. Originally, we expected that it can reduce the surface roughness which made the interface between floating gate and channel layer become well. However, the results showed it didn’t enhance the electrical and switching properties. On the contrary, the memory window became smaller. We attributed these results to the PMMA- PMMA:GQDs interface was not good and the total PMMA-PMMA:GQDs-SiO2 three layers was so thick that made the gate control decline.

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