低功率CO_2激光辐照对多层石墨烯结构的影响

Effects of Low Power CO_2 Laser Irradiation on Structure of Multilayer Graphene

在真空环境下使用不同功率密度的CO2激光对化学气相沉积法(CVD)生长的石墨烯进行辐照,通过研究辐照前后的拉曼光谱变化考察了激光功率密度及辐照时间对多层石墨烯结构的影响。结果表明,当功率密度较低(13W/cm2)时,石墨烯拉曼光谱中的D峰降低,2D峰增强,石墨烯内的掺杂、缺陷减少。随着功率密度的增加,石墨烯的缺陷增多,部分缺陷连接形成晶界,使石墨烯分解为纳米晶。在58 W/cm2的功率密度下,当作用时间为120s时,在石墨烯表面产生非晶碳。研究表明,适当参数的CO2激光辐照能改善石墨烯的内在性能。

Multilayer graphene generated by chemical vapor deposition （CVD） method is irradiated by CO2 laser in vacuum with different power densities and irradiation time. Raman spectroscopy is used to clarify the influences of laser power density and irradiation time on the structure modification. At a laser power density of 13 W/cm2 , the decrease of D-band and the increase of G-band intensity are due to the reduction of defects. In contrast, the sample irradiated with higher power density shows that the D-band intensity increase dramatically caused by the laser thermal effects. Nanocrystalline graphene is formed as the defects after irradiation at higher power desities. With increasing irradiation time to 120 s, amorphous carbon is formed at the surface of graphene at a lase power density of 58 W/cm2. These results show that proper irradiation of CO2 laser can improve the charactervstics of graphene.