Processing of Monolayer Materials Via Interfacial Reactions

Abstract

A method of forming and processing of graphene is disclosed based on exposure and selective intercalation of the partially graphene-covered metal substrate with atomic or molecular intercalation species such as oxygen (O 2 ) and nitrogen oxide (NO 2 ). The process of intercalation lifts the strong metal-carbon coupling and restores the characteristic Dirac behavior of isolated monolayer graphene. The interface of graphene with metals or metal-decorated substrates also provides for controlled chemical reactions based on novel functionality of the confined space between a metal surface and a graphene sheet.

1 . A method of processing graphene, the method comprising,
 providing a graphene layer in which graphene interacts with a surface of a metal substrate under the graphene layer;   exposing the surface of the metal substrate to an ambient gas; and   tuning the graphene-substrate interaction by interfacial reaction of the ambient gas on the surface of the metal substrate.   
     
     
         2 . The method of  claim 1 , wherein the metal substrate is selected from the group consisting of ruthenium (Ru), nickel (Ni), platinum (Pt), iridium (Ir), copper (Cu), cobalt (Co), iron (Fe), Palladium (Pd), and rhodium (Rh). 
     
     
         3 . The method of  claim 1 , wherein the ambient gas is selected from the group consisting of oxygen (O 2 ), nitrogen oxide (NO 2 ), nitrogen (N 2 ), hydrogen (H 2 ), chlorine (Cl), fluorine (F), bromine (Br), iodine (I), ammonia (NH 3 ). 
     
     
         4 . The method of  claim 1 , wherein tuning the graphene-substrate interaction comprises
 intercalating the ambient gas between the graphene layer and the surface of the metal substrate at temperatures below 400° C.; and   decoupling the graphene from the metal substrate as a result of the ambient gas intercalation.   
     
     
         5 . The method of  claim 4 , further comprising:
 reversing the intercalation of the ambient gas between the graphene layer and the surface of the metal substrate by raising the metal substrate to a temperature above 400° C.   
     
     
         6 . The method of  claim 4 , wherein the intercalation under the ambient gas on the surface of the metal substrate occurs at temperatures between about 20° C. and 400° C. 
     
     
         7 . The method of  claim 5 , wherein reversing the intercalation occurs between about 400° C. and the melting point of the metal substrate. 
     
     
         8 . The method of  claim 4 , wherein the decoupling of the graphene is accomplished by a selective oxidation of the metal surface. 
     
     
         9 . The method of  claim 4 , wherein the decoupling of the graphene is accomplished by nitridation, hydrogenation, or reaction with Cl, F, Br, or I. 
     
     
         10 . The method of  claim 4 , wherein the ambient gas is an atomic gas, a gas of diatomic or larger molecules, or a gas of molecules that break down into atoms or smaller (diatomic or larger) molecules between the graphene layer and the metal substrate surface. 
     
     
         11 . The method of  claim 4 , wherein the ambient gas is nitrogen oxide (NO 2 ). 
     
     
         12 . The method of  claim 11 , wherein the nitrogen oxide (NO 2 ) forms a diatomic NO gas in a space between the graphene layer and the metal substrate. 
     
     
         13 . The method of  claim 1 , wherein tuning the graphene-substrate interaction comprises restoring a characteristic Dirac behavior of isolated graphene, wherein graphene is monolayer, or has related charge-carrier characteristics of bilayer graphene, few-layer graphene or multilayer graphene. 
     
     
         14 . The method of  claim 1 , wherein tuning the graphene-substrate interaction comprises electrically isolating the graphene layer from the metal substrate. 
     
     
         15 . The method of  claim 14 , wherein electrically isolating the graphene layer from the metal substrate comprises forming a dielectric between the graphene layer and the metal substrate. 
     
     
         16 . A method of processing graphene via interfacial reactions, the method comprising,
 providing a graphene layer in which graphene interacts with a surface of a metal substrate under the graphene layer;   exposing the surface of the metal substrate to an ambient gas,   the metal substrate selected from the group consisting of ruthenium (Ru), nickel (Ni), platinum (Pt), iridium (Ir), copper (Cu), cobalt (Co), iron (Fe), palladium (Pd), and rhodium (Rh) and the ambient gas selected from the group consisting of oxygen (O 2 ), nitrogen oxide (NO 2 ), nitrogen (N 2 ), hydrogen (H 2 ), chlorine (Cl), fluorine (F), bromine (Br), iodine (I), and ammonia (NH 3 ); and   tuning the graphene-substrate interaction by interfacial reaction of the ambient gas on the surface of the metal surface,   wherein tuning the graphene-substrate interaction comprises:   intercalating the ambient gas between the graphene layer and the surface of the metal substrate at temperatures below 400° C.; and   modifying the graphene-substrate interaction or decoupling the graphene from the metal substrate as a result of the ambient gas intercalation.   
     
     
         17 . The method of  claim 16 , further comprising:
 reversing the intercalation of the ambient gas between the graphene layer and the surface of the metal substrate by raising the metal substrate to a temperature above 400° C.   
     
     
         18 . A method of performing chemical reactions at an interface between graphene and a metal, the method comprising,
 exposing a surface of a metal substrate under a graphene layer to chemical species chosen from the group consisting of atomic species, molecular species, and a combination thereof;   performing chemical reactions of the chemical species with each other or with the surface of the metal substrate in a space beneath the graphene layer by intercalation, and   regulating intercalation by varying reaction parameters of partial pressures of all chemical species, sample temperature, and sequence of exposure to different reactant species, which can be simultaneous or sequential with different waiting and exposure times.   
     
     
         19 . The method of  claim 18 , wherein the graphene layer provides steric hindrance, limits access of atomic and molecular species based on size, and controls orientation of the atomic and molecular species. 
     
     
         20 . The method of  claim 18 , wherein the metal substrate is a transition metal. 
     
     
         21 . The method of  claim 20 , wherein the transition metal is selected from the group consisting of ruthenium (Ru), nickel (Ni), platinum (Pt), iridium (Ir), copper (Cu), cobalt (Co), iron (Fe), palladium (Pd), and rhodium (Rh). 
     
     
         22 . The method of  claim 18 , wherein the molecular species are selected from the group consisting of oxygen (O 2 ), nitrogen oxide (NO 2 ), nitrogen (N 2 ), hydrogen (H 2 ), chlorine (Cl), fluorine (F), bromine (Br), iodine (I), and ammonia (NH 3 ). 
     
     
         23 . The method of  claim 18 , wherein the atomic species are selected from the group consisting of silicon (Si), boron (B), aluminum (Al), zinc (Zn), chromium (Cr), titanium (Ti), zirconium (Zr), hafnium (Hf), scandium (Sc), yttrium (Y), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sa), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), and ytterbium (Yb). 
     
     
         24 . The method of  claim 18 , wherein regulating intercalation comprises:
 allowing the intercalation of the atomic or molecular species on the surface of the metal substrate at temperatures below 400° C.;   decoupling the graphene from the metal substrate as a result of the intercalation; and   reversing the intercalation of the atomic or molecular species on the surface of the metal substrate by raising the temperature above 400° C.   
     
     
         25 . The method of  claim 18 , wherein the space beneath the layer of graphene has a height between 1.8 Å and 4 Å.