二維材料量子點的負微分電阻研究

Negative Differential Resistance of 2D-Materials Based Quantum Dots

陳雨廷(Yu-Ting Chen)

指導教授 ： 沈志霖

中原大學/理學院/物理研究所/碩士(2021年)

https://doi.org/10.6840/cycu202100667

摘要

負微分電阻元件因其在開關、儲存元件以及類比數位轉換器中的潛在應用引發了廣大的討論。對於一個負微分電阻元件，最重要的是可控的負微分電阻。本論文使用兩種二維材料，分別是石墨烯及二硫化鎢，並成功利用雷射消融法合成了石墨烯量子點及二硫化鎢量子點。在-4到4 V的外加電壓下的電壓-電流量測中，在石墨烯量子點及二硫化鎢量子點產生明顯的負微分電阻，它們的的負微分電阻峰谷比分別達到3.5及10.1。藉由控制電壓掃描速率、氣壓可以來調控負微分電阻的峰值特徵及峰谷比。添加雙氧水對於負微分電阻影響靈敏，雙氧水濃度增加時，負微分電阻峰谷比會增加。此外，當電壓掃描速率增加時，負微分電阻峰谷比也會增加。我們認為，由量子點團聚所引起的陷阱態可增加電荷載子的穿隧，是量子點中產生負微分電阻的主要原因。在經過五十次的電壓-電流量測循環後，石墨烯量子點及二硫化鎢量子點的負微分電阻仍保有高的峰谷比，這項研究對於開發二維材料的負微分電阻相關元件將有所幫助。

關鍵字

石墨烯 ； 二維材料 ； 量子點 ； 負微分電阻

並列摘要

Negative differential resistance (NDR) plays an important role in electronic components such as switches, memory devices, and analog-to-digital converters. Such a wide range of applications has incited profound interest in the study of NDR. Controlling the NDR property is one of the most important issues to be investigated. In this paper, two-dimensional materials such as graphene and tungsten disulfide (WS2) were utilized for NDR study. Here, graphene quantum dots (GQDs) and tungsten disulfide quantum dots (WS2 QDs) were fabricated via by pulsed laser ablation (PLA) method. After PLA fabrication, the current-to-voltage (I-V) measurements shows that both GQDs and WS2 QDs exhibit obvious NDR phenomena. The NDR peak-to-valley ratio reached 3.5 and 10.1 for GQDs and WS2 QDs, respectively, under the applied voltage from -4 to 4 V. The peak characteristics and peak-to-valley ratio of NDR can be adjusted by controlling the voltage sweep rate and air pressure. Further, the introduction of hydrogen peroxide demonstrates visible effects on the NDR. When the concentration of hydrogen peroxide increases, the peak-to-valley ratio of the NDR will increase as well. Lastly, when the voltage sweep rate increases, the peak-to-valley ratio of the NDR also increases. Based on this study, we suggest that the trap state caused by the agglomeration of quantum dots can increase the tunneling of charge carriers, which is the origin of the NDR behavior in quantum dots. After fifty I-V measurement cycles, the NDR of GQDs and WS2 QDs displays a stable high peak-to-valley ratio. This research suggests that GQDs and WS2 QDs two-dimensional materials fabricated by PLA could be helpful for the future development of NDR-based devices.

並列關鍵字

Graphene ； 2D-materials ； Quantum dots ； Negative differential resistance

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