Effect of charged metal nanoparticles on carrier injection in graphene by an external electric field

Abstract

First-principles total-energy calculations clarified the effect of charged Al nanoparticles on carrier accumulation in graphene by an external electric field. Carrier injection in graphene with Al nanoparticles is sensitive to the relative position of the Al nanoparticles to the gate electrode. The nanoparticles sandwiched between graphene and electrode prevent the carrier injection in graphene, while the nanoparticles adsorbed on the opposite side do not affect the Dirac point shift, resulting in the successive carrier injection in graphene.Because of the density of state difference, the capacitance of graphene with Al nanoparticle also depends on the electrode position.Graphene has been keeping a premier position not only in the low-dimensional sciences but also in the electronic device engineering due to its unique structural and electronic properties. [1][2][3][4][5][6][7][8] For the fundamental and applied sciences of graphene, it is mandatory to precisely control their electronic structure by external conditions, such as chemical modification, atom/molecule doping, and external electric field. In particular, the band gap engineering and the Fermi level tuning are highly important for fundamental study and application of graphene. In practical application of graphene, graphene inherently possesses hybrid structures with foreign materials in its device structures, such as insulating substrate, metal electrode, and atoms/molecules, which affect the electronic structure of graphene. [11][12][13][14][15][16][17][18] It has been demonstrated that graphene physically adsorbed on insulating substrates does not possesses the Dirac cone but quadratic dispersion band with a finite energy gap which depends on the surface morphology and atom species. [12][13][14][15] Atoms and molecules adsorbed on the graphene also modulate the Dirac cone of graphene by covalent and van der Waals interaction between adsorbates and graphene. [16][17][18] Although the carrier accumulation in pristine graphene and graphite under an external electric field has been steadily elucidated, 19,20

Field-induced structural control of COx molecules adsorbed on graphene

“…[1][2][3] With this peculiar electronic structure around the Fermi level, graphene exhibits remarkable carrier mobility [4][5][6] of up to 200 000 cm 2 V -1 s -1 that enables high-speed switching within electronic devices. 7 Nevertheless, the electronic structure of graphene is fragile against the formation of hybrid structures with foreign materials, such as insulating substrates, [8][9][10][11] metal electrodes, 12 molecular/atomic adsorbates, [13][14][15][16][17][18][19][20][21] and structural defects. [22][23][24][25][26] Furthermore, an external electric field can tune the electronic structure of graphene and its hybrids.…”

Carrier injection in nonbonding π states of N-doped graphene by an external electric field

“…The electric field further increases the degree of freedom to control the electronic properties of graphene hybrids; bilayer graphene is a semiconductor with the direct gap under the electric field normal to the layer. [20][21][22][23][24][25] The Fermi level is pinned at the energy corresponding to the electronic states of the charge impurity adsorbed on graphene or the dangling bond states in graphene. 24,25) The findings indicate that the electronic properties of graphene hybrids depend on their detailed structure and electric field.…”

“…[20][21][22][23][24][25] The Fermi level is pinned at the energy corresponding to the electronic states of the charge impurity adsorbed on graphene or the dangling bond states in graphene. 24,25) The findings indicate that the electronic properties of graphene hybrids depend on their detailed structure and electric field. N-doped graphene is one of the representative hybrids exhibiting unusual electronic properties that are applicable to electronic and catalytic devices.…”

Geometric structures of Al nanoparticles adsorbed on graphene under an external electric field

“…In our previous work, such hybrids under an electric field endow versatile electronic properties that are absent in an isolated graphene. 24,25) In graphene thin films, one of whose layers possesses defects, the Fermi level is sensitive to the relative arrangement of the defective graphene layer and the carrier species, leading to the Fermi level pinning for hole doping. 24) Charged nanoparticles adsorbed on graphene surfaces also provide unique electronic properties under carrier injection by the gate electrode.…”

“…24) Charged nanoparticles adsorbed on graphene surfaces also provide unique electronic properties under carrier injection by the gate electrode. 25) Despite the fact that the electronic structure of such hybrids under an electric field has been elucidated, the detailed energetics and geometric structures of hybrids under the electric field have not been well examined in detail yet. Thus, in this work, we aim to elucidate the geometric structures of Al nanoparticles adsorbed on graphene under excess electron or hole injection by a counter electrode using the density functional theory (DFT) combined with the effective screening medium (ESM) method.…”