| Summary: | 碩士 === 國立中正大學 === 光機電整合工程研究所 === 105 === Graphene is a suitable material in the application of photodetectors due to its excellent physical properties. However, it has the disadvantage of a weaker photoresponse. In this study, the photoresponse of graphene is enhanced through the spin coating of titanium dioxide (TiO2). Although TiO2 have superior photoresponse performance in ultraviolet region, due to the limit of its energy gap, there is almost no photoresponse in visible light region. In this study, we produce graphene composite device by growing cadmium sulfide (CdS) through Successive Ionic Layer Adsorption and Reaction (SILAR) method. Utilizing the absorption of CdS in visible light region, we are able to enhance the photorepsonse of the grapheme composite device in both ultraviolet and visible light region.
In this study, we fabricated and measured the optoelectronic properties of both CdS/G and CdS/TiO2/G composite device. The results show that CdS/TiO2/G composite device have the best photoresponse performance under 365 nm LED light source. Thus, we measure the device’s properties under different voltage and optical intensity. We also measure the full spectral response of CdS/TiO2/G composite device under Xenon light source. We discover that the device have great photoresponse performance under wavelength from 300 nm to 600 nm, over 100A/W in 300 nm to 500 nm region with the best value of 889.2 A/W under 300 nm. This prove that utilizing CdS and TiO2, we are able to significantly increase the photoreponse of graphene devices.
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