Doping graphene with metal contacts pdf

Doping graphene with metal contacts radboud universiteit. Computational study of metal contacts to monolayer. Low and reproducible metalgraphene contact resistance r c i. An article includes a layer of graphene having a first work function. Recently, a lot of effort has been focused on improving the performance and exploring the electric properties of graphene. Contact resistance at planar metal contacts on bilayer. This possible damage due to the probes could be avoided by depositing metal contacts on the graphene instead of using the probes directly on the graphene. Understanding noninvasive charge transfer doping of. Recent citations reversible doping of graphene field effect transistors by molecular hydrogen. In this work, we systematically investigate and compare noninvasive doping of chemical vapor deposition graphene with three molecule dopants through spectroscopy and electrical conductivity techniques. Metalsemiconductormetal photodetectors based on graphenep. Until now, fermi level pinning of monolayer tmdcs has been reported only theoretically, although that of bulk tmdcs has been reported. We report an enhancement of the bonding energy of weakly interacting metals by using a metalgraphenemetal sandwich geometry, without sacrificing the intrinsic. Only a small fraction of all available metals has been used as electrode materials for carbonbased devices due to metalgraphene interface debonding problems.

They investigated samples of the carbon compound enriched with the foreign. Fermi level pinning at electrical metal contacts of monolayer. Effect of noblemetal contacts on doping and band gap of. However, in order to use graphene in possible applications such as photodetector, photovoltaics. Densityfunctional theory of graphene predicts that noble metal contacts will provide doping but leave the dirac crossing point intact. Inversely, the oxygen affinity of softer metals increases. Spatially controlled electrostatic doping in graphene pi. In particular, its unique 2d sp 2hybridized networks of carbon atoms arranged in a honeycomb lattice make graphene potential for exceptional electronic quality. Electrical metal contacts to twodimensional 2d semiconducting transition metal dichalcogenides tmdcs are found to be the key bottleneck to the realization of high device performance due to strong fermi level pinning and high contact resistances rc. Fermi level pinning at electrical metal contacts of. More detailed dft simulations suggest that the dipole formed due to charge redistribution at the interface between the metal and graphene shifts the charge neutrality point i. Thionyl chloride shows the smallest improvement in conductivity with poor temporal and thermal stability and nitric acid induces the biggest sheet resistance reduction with modified stability.

Electrical properties of graphenemetal contacts scientific. Since o2 binding energies are correlated with the co oxidation barrier in a volcanolike trend. Low and reproducible metal graphene contact resistance r c i. Thus, optimizing the contacts between 2d semiconductors and metal electrodes is an important technological challenge. We use density functional theory to study how graphene is doped by adsorption on metal substrates and find that weak bonding on al, ag, cu, au, and pt, while preserving its unique electronic structure, can. The doping devices are very vulnerable to environment, especially for n. Doping graphene with metal contacts open access library.

Reduced work function of graphene by metal adatoms arxiv. However, from this plot it is not possible to evaluate the metal induced g doping, since it is not straightforward to distinguish between the charge belonging either to graphene or to the cu contact 8. Crystals free fulltext a study on graphenemetal contact. Ee311 saraswat ohmic contacts 2 conduction mechanisms for metal semiconductor contacts ef v i ohmic schottky c field emission. Effective graphene doping depends on substrate material. Properties of graphenemetal contacts probed by raman. The doping of graphene by metallic contacts is well established.

Fischer b, david prendergast d and sarbajit banerjee a a department of chemistry, university at buffalo, the state university of new york, buffalo, new york 142603000, usa. In first approximation, this can be described by charge transfer between the metal and graphene due to differences in work functions. Conduction mechanisms for metalnsemiconductor contacts as a function of the barrier height and width. Juelich physicists have discovered unexpected effects in doped graphene i. Densityfunctional theory of graphene predicts that noblemetal contacts will provide doping but leave the dirac crossing point intact. Figure 10 shows a quantification of doping stability with temperature. Ultralow specific contact resistivity in metalgraphene. The doping level could not easily be easily controlled. Heavy hole doping on graphene with concentration as high as 1. Most of doping methods could considerably damage carrier mobilities of graphene. Pdf making devices with graphene necessarily involves making contacts with metals. Metalsemiconductor ohmic contacts stanford university. Metalsemiconductormetal photodetectors based on grapheneptype silicon schottky junctions yanbin an,1,a ashkan behnam,2,a eric pop,2,3 and ant ural1,b 1department of electrical and computer engineering, university of florida, gainesville, florida 32611, usa 2department of electrical and computer engineering, micro and nanotechnology lab, university of illinois at urbanachampaign, urbana. On chemical bonding and electronic structure of graphene metal contacts.

Figure 7 shows the calculated doping for the different mg contacts and for several d values down to the med of each structure. Thus, there is the need of estimating the graphene doping due to the metal proximity. Our model explains the spread in experimental results as due to uncontrolled graphene doping and suggests. We use density functional theory to study how graphene is doped by. This article presents a summary of chemical doping of graphene aimed at tuning the electronic properties of graphene. To overcome this issue, several studies on specific cases of metal tmd contacts have been. We use highresolution angleresolved photoemission and.

Young1, 1national graphene institute and school of materials, university of manchester, oxford road, manchester m 9pl, uk 2global energy interconnection research institute europe gmbh, berlin, germany received. Thermionic emission dominates the transport across the junctions above 260k with a zerobias barrier height of 0. And ndoping said graphene with a vapor comprising an ntype dopant or a doping solution comprising an ntype dopant, an ndoping method of graphene produced thereby, doped graphene. Our treat ment of metalgraphene mg contacts captures the follow ing. Jun 01, 2010 ultrathin carbon layers known as graphene show promise as the basis for a host of extremely small and efficient electronic devices. Graphene surface contacts of tin disulfide transistors for. Achieving low resistance contacts and high carrier mobility are common concerns for obtaining high performance of graphene devices. A photocurrent response at graphenemetal contacts has been reported by various groups, including ours25, and in these early reports the origin of photocurrent generation. Electrons are transferred from the layer of graphene to the metal oxide film, forming a hole accumulation layer in the layer of graphene. However, the formation of lowresistance metal contacts is the biggest challenge that masks the innate exceptional electronic and magnetic properties of 2d semiconductors, due to their band gaps and pristine surfaces, as well as lack of proper doping approach.

In graphene fets gfets, the work functions wf of electrode materials and metalgraphene mg contact configurations have remarkable influences on contact properties of mg. Improved contact resistivity and enhanced mobility of. This contact scheme is applied to a grapheneperovskite hybrid photodetector, significantly improving its performance 0. For example, exposing the graphene to a mild o 2 plasma yields an order of magnitude improvement in the contact resistivity. Metalgraphenemetal sandwich contacts for enhanced interface. The effect of vacuum annealing on the properties of graphene is investigated by using raman spectroscopy and electrical measurement. Open access publications 51571 freely accessible full text publications. The contact resistance between graphene and metal electrodes is crucial for the achievement of highperformance graphene devices. We use density functional theory to study how graphene is doped by adsorption on metal substrates and find that weak bonding on al, ag, cu, au and pt, while preserving its uniqu.

Graphene nanoribbons long strips only tens of nanometers in width are readily pdoped by adsorbates from the ambient atmosphere. In this paper, the work function of graphene doped by different metal adatoms and at different. We use density functional theory to study how graphene is doped by adsorption on metal substrates and find that weak bonding on al, ag, cu, au. The potential applications in electronic devices of graphene single atom, thick layers of graphite would be even greater if it can be accessed in both p and ndoped forms. Mar 29, 2016 juelich physicists have discovered unexpected effects in doped graphene i. To overcome this issue, several studies on specific cases of metaltmd contacts have been. Understanding noninvasive charge transfer doping of graphene. Making devices with graphene necessarily involves making contacts with metals. On chemical bonding and electronic structure of graphene. Electrostatic doping of the graphene further reduces contact resistivity from 519 to 45.

Jul 11, 2017 low and reproducible metalgraphene contact resistance r c i. Graphene is one of the most promising materials for postsilicon electronics and has outstanding physical and electronic properties. Doping graphene with metal contacts university of twente. When the graphene doping is homogeneous, the photocurrent will be zero.

Spatially controlled electrostatic doping in graphene pin. The chemical vapour deposition process allows the synthesis of large area graphene. Nov 26, 2018 specific contact resistivity is reduced from 72. Ndoping of graphene through electrothermal reactions with. Cu and ni induce ntype doping in graphene, while, for the au contact, graphene becomes ptype. Ultrathin carbon layers known as graphene show promise as the basis for a host of extremely small and efficient electronic devices. Sorry, we are unable to provide the full text but you may find it at the following locations. We use density functional theory to study how graphene is doped by adsorption on metal substrates and find that weak bonding on al, ag, cu, au, and pt, while preserving its unique electronic structure, can still shift the fermi level with respect to the conical point by approximately 0. But in order to create a useful component, the electronic. Our scanning gate measurements also demonstrate graphenes excellent capability to sense the local electric. Extremely low contact resistance on graphene through n. Pdf doping graphene with metal contacts researchgate. Conduction mechanisms for metal nsemiconductor contacts as a function of the barrier height and width. This doping is due to the h2oando2 adsorption on graphene, and.