多層二氧化鈦摻雜堆疊石磨烯紫外線光偵測器製備與光電特性研究

Optoelectric Characteristics Studies and Synthesize of Layer By Layer TiO2/Graphene Composite UV Photodetector

黃國智(Guo-Jhih Huang)

指導教授 ： 丁初稷

國立中正大學/工學院/光機電整合工程研究所/碩士(2015年)

摘要

本文首先以 CVD 法將石墨烯成長在銅箔上，之後再將其轉印至玻璃基板上以製備石墨烯光偵測器，而為了提升紫外光波段的吸收我們使用液滴塗覆法 (Drop coating) 將二氧化鈦溶液沉積在石墨烯光偵測器上製程石墨烯複合材料光偵測器，而為了探討不同堆疊層數所帶來的效應，我們將重複轉印石墨烯與沉積二氧化鈦來獲得多層的堆疊結構，本碩論目的在探討堆疊不同層數的石墨烯與二氧化鈦結構對光偵測器的光電特性影響。
　　由實驗結果可知，在 365 nm LED 照射下，未沉積二氧化鈦薄膜前石墨烯光測器的響應率 (responsivity)、電流開關比 (on-off ratio) 分別為：-2.454 A/W、-9.9%；而四層二氧化鈦摻雜石墨烯多層結構時會有最好的光電特性，如：響應率 (responsivity)、上升及下降時間 (rising/falling time) 電流開關比 (on-off ratio) 分別為：179.53 A/W (@365 nm 0.75 uW)，5.94 s、45.98 s、Iphoto/Idark = 23.7% (@365 nm 34 mW)，推測出的原因為當二氧化鈦奈米顆粒吸收了 UV 光的能量後，其產生的電子電洞對能夠被石墨烯收集，而石墨烯也不受到氧脫附的影響，使的整體電流上升，進而讓整體的光電特性提高。

關鍵字

石墨烯

並列摘要

In this study, TiO2/graphene composite photodetector was synthesized by four steps which involved firstly graphene was grown on polished copper foil by chemical vapor deposition (CVD) technique, followed by transferring the graphene onto glass substrate. The third step was to increase the UV absorption by drop cast TiO¬2 on graphene and finally, second step and third steps were repeated to increase the number of layer-by-layer of TiO2/graphene.
The effect and optoelectronic characteristic of different TiO2/graphene layers composite photodetector were studied. The responsivity and on-off ratio of the synthesized devices were measured under 365 nm Light Emitting Diode (LED) light irradiation. The responsivity of the device was found as -2.454 A/W, whereas the on-off ratio was measured as –9.9%. The best device was found to be the 4-layer stacking layer-by-later TiO2/graphene which has the best responsivity, rising time and falling time, and on-off ratio with the value of 179.53 A/W, 5.94 s, 45.98 s, and Iphoto/Idark = 23.7%, respectively. The reasons may due to the excitation of photo electron-hole pairs caused by ultraviolet light irradiation and were collected efficiently by graphene. Besides, the photocurrent and optical properties were greatly enhanced due to absence of oxygen on the surface of graphene.

並列關鍵字

graphene

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