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

• Main Authors: Guo-Jhih Huang, 黃國智
• Other Authors: Chu-Chi Ting
• Format: Others
• Language: zh-TW
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/bcrej3

碩士 === 國立中正大學 === 光機電整合工程研究所 === 103 === 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.