Selective area chemical vapor deposition of graphene

For more than half a century silicon-based CMOS transistors have been scaled continuously to fulfill the projections of Moore’s law and served as the backbone of semiconductor electronics. This scaling trend, however, is now approaching fundamental limits on computing speed and energy efficiency. Due to their unique properties, two dimensional (2D) materials, especially graphene and transition metal dichalcogenides (TMDCs), offer great opportunities for developing “beyond CMOS” electronic devices and other future electronic and photonic devices. However, there are still several critical challenges for graphene applications, such as mass production of high-quality single-crystal graphene films, bandgap opening, and heterostructure integration with other 2D materials. Chemical vapor deposition (CVD) of graphene is the most promising way by far for the synthesis of large-scale single-crystal graphene. In this dissertation, we study the low-pressure chemical vapor deposition (LPCVD) of graphene on commercial copper foils and develop a new graphene growth method called selective area chemical vapor deposition of graphene (SACVD). This SACVD method is a one-step seed-free method that can synthesize graphene on selective areas of the copper catalytic substrate by using a quartz mask. We study the growth model of the SACVD graphene growth and propose a growth mechanism to understand the SACVD growth of graphene. In SACVD graphene grows on both the front and back sides of the Cu foil that is sandwiched between the quartz mask and substrate. Furthermore, the graphene that grows on both sides of the copper foil shares the same pattern as defined by the smaller topside quartz mask. Based on this experimental observation, the proposed mechanism is that the oxygen released by the fused quartz accumulates sufficiently to promote graphene growth only in the regions where both sides of the copper foil are masked by quartz. The high diffusion coefficient of oxygen through copper would prevent this accumulation if fused quartz were placed on only one side of the copper foil. This SACVD method can be applied to the growth of an ordered array of large-size single-crystal graphene domains, and potentially to the growth of other 2D materials. Based on the SACVD growth of single crystal graphene, we also propose a continuous growth method to grow large-size single-crystal graphene controlled by a moving quartz mask. To pattern graphene at the nanoscale for bandgap opening and device fabrication, we also study atomic force microscope tip-based nanolithography methods and find that different types of localized chemical reactions, such as electrochemical oxidation and catalytic etching, can be induced by AFM tips under different conditions