Hydrogen-dominated metal-free growth of graphitic-nitrogen doped graphene with n-type transport behaviors

Controllable nitrogen doping, an effective way to regulate the electronic property of graphene, has been achieved on metal catalyst which needs to be removed by additional processes when fabricating electronic devices, giving rise to structural damages and contaminations. Here, by using pyridine as the sole source of carbon and nitrogen, a metal-free thermal chemical vapor deposition method is demonstrated to synthesize nitrogen-doped graphene (NG) on dielectrics (SiO₂/Si, quartz, rock crystal, and sapphire). It is discovered that increasing H₂ flow could promote the quality of graphene and the proportion of graphitic-N. At an optimal growth temperature of 1000 °C, we realize the controllable synthesis of graphitic-N doped graphene. Impressively, field-effect transistors directly fabricated from the N-doped graphene (∼1.1%) films on SiO₂/Si exhibit strong n-type semiconducting behaviors with electron mobilities of 110–283 cm² V⁻¹ s⁻¹ in air, rivaling heavily doped NG grown on metals. As revealed by density functional theory calculations, compared with NG with multiple types of nitrogen atoms, single graphitic-N doping leads to more prominent n-type transport behaviors, owing to the absence of p-type pyrrolic-N and pyridinic-N.