Controlled Synthesis Of Graphene For Nano-optoelectronic Devices Application

Graphene, a novel two-dimensional material, is regarded as one of the most promising candidates for future nanoelectronics due to its atomic thickness, excellent properties and widespread applications. Growth and transfer of large-area graphene successfully are the basis of the applications of graphene. However, there are many technical difficulties on the factual applications. It is not only about growth and transfer of large-area graphene perfectly, but also about improving the performance of the devices based on graphene. In light of these difficulties, the author explored the methods of synthesis and transfer of large area graphene, and investigated the optoelectronic devices based on graphene deeply. Related research results are as follows:1. Synthesis and transfer of large-area graphene were systematic studied, and the synthetic conditions of growth graphene on Cu foil substrate were found out, obtaining the signal curve figure and illustrating the synthesis mechanism of the growth process of graphene. At the same time, we explored the transfer methods of large-area graphene, including dry transfer method and wet transfer method. We obtained the ideal demand after improving the both transfer methods. At last, we gave the specific experiment conclusion of the etching solution of growth graphene on Cu foil substrate.2. Self-driven and high-speed near infrared detector was prepared by combining the CVD-graphene and GaAs and utilizing the passivation technology. The AlOx passivation layer was used for preparing the BLG/AlOx/GaAs Schottky junction. Electrical analysis reveals that the AlOx passivated NIRPD exhibits high sensitivity to 850 nm illumination at zero bias voltage. The dark current was reduced considerably, while the responsivity was increased after passivation. It is also observed that the detectivity of the NIRPD with AlOx was estimated to be 2.88×1011 cm Hz1/2 W-1, respectively, much more improved than the NIRPD without AlOx (7.3×109cm Hz1/2 W-1). In addition, further device analysis shows that the NIRPD with AlOx can work in an ultra-wide range of switching frequencies and ultra-fast response speed (τr=320 ns,τf=380 ns), which is far faster than those of without AlOx.3. High PCE solar cells were prepared by combining the CVD-graphene and CdSe nanoribbons and utilizing plasmon resonance enhancement effect. The PCE of the schottky junction of bilayer graphene and CdSe nanoribbons was 0.4%, improved to 4.35% after the Au particle decorated on the CdSe nanoribbons. By absorption spectroscopy, the absorption of the CdSe nanoribbons for light became strong after the Au decorated. Through the analysis of the band of the BLG/n-CdSe, we found the mechanism formation of the nano-solar cell.