Keywords:graphene, ion beam, charge transport
Electron transport property in graphene can be tuned by introducing crystalline defects, and helium ion beam irradiation is an excellent method to generate point defects in graphene. By using helium ion microscope (HIM), defect formation with a very high spatial resolution is possible, and also, the total dose of ions applied to graphene can be precisely controlled by tuning the ion irradiation conditions. However, the precise mechanism of carrier transport tuning by defect generation is not fully understood. In order to investigate the carrier transport property in defective graphene, we have developed a technique of real-time detection of electric conduction in graphene during helium ion beam irradiation. In this presentation, we show the dependence of carrier conduction on the length of irradiated region. Recent results in the analysis of carrier transport property will also be presented.