Fig. 1. XPS C_{1 s} peak spectra of graphene samples: (a) Unirradiated; (b) 0.7 × 10¹³ He⁺/cm²; (c) 1.6 × 10¹³ He⁺/cm²; (d) 2.5 × 10¹³ He⁺/cm². 石墨烯样品XPS C_{1 s}峰谱图　(a)未辐照; (b) 0.7 × 10¹³ He⁺/cm²; (c) 1.6 × 10¹³ He⁺/cm²; (d) 2.5 × 10¹³ He⁺/cm²

Fig. 2. The Raman spectra of unirradiated graphene.未辐照石墨烯Raman光谱图

Fig. 3. The Raman spectra of graphene before and after He⁺ irradiation. He⁺辐照前后石墨烯Raman光谱图

Fig. 4. The relationship between Raman peak strength I_D/I_G, I_2D/I_G ratio and irradiation dose. Raman峰强I_D/I_G, I_2D/I_G比值与辐照剂量的关系

Fig. 5. Electrical conductivity versus gate voltage at different irradiation doses.不同辐照剂量下电导率随栅极电压变化曲线

Fig. 6. The relation between Dirac voltage variation and irradiation dose.狄拉克电压偏移量与辐照剂量的关系