Current modulation in graphene p–n junctions with external fields

Abstract

In this work we describe a proposal for a graphene-based nanostructure that modulates electric current even in the absence of a gap in the band structure. The device consists of a graphene p-n junction that acts as a Veselago lens that focuses ballistic electrons on the output lead. Applying external (electric and magnetic) fields changes the position of the output focus, reducing the transmission. Such device can be applied to low power field effect transistors, which can benefit from graphene's high electronic mobility.

Análogos eletrônicos de dispositivos ópticos em grafeno: da junção p-n à lente de Veselago

“…Os potenciais de porta nas diferentes regiões da junção p-n atuam de forma similar a índices de refração diferentes, permitindo a ocorrência de diversos efeitos interessantes, a saber, transmissão perfeita (nula) em uma barreira de potencial em monocamada (bicamada) de grafeno para incidência normal, efeito conhecido como tunelamento Klein [7] (anti-Klein [8]), refração negativa [9] e outros. Tais efeitos podem ser usados para modelar dispositivos eletrônicos que atuam como moduladores [10][11][12][13], comutadores [14][15][16][17] e portas lógicas [18][19][20][21].…”

Time-dependent transport in Graphene Mach-Zender Interferometers

“…However, in recent years the purity of graphene samples has substantially improved, thanks to new production techniques such as the encapsulation with hexagonal Boron Nitride (hBN) [18,19]. This has made it possible to create very clean pn junctions in nanoribbons of monolayer graphene, and study transport phenomena in the Quantum Hall regime: among these, the coexistence between Edge States and Snake States along pn junctions [20][21][22][23][24][25][26][27][28][29], and the occurrence of Klein tunneling through electrostatic barriers [29][30][31][32][33].…”

Time-dependent transport in graphene Mach-Zender interferometers

“…LL splitting also allows to observe many kinds of collective excitations, such as magnons [13][14][15], valley skyrmions [16], and even strain-induced pseudomagnetoexcitons [17]. For these reasons, graphene has recently raised much attention in the field of electronic quantum optics [18][19][20][21][22][23][24][25][26] in the integer and fractional quantum Hall regimes [20], and offers promising perspectives for quantum computation as well [27]. The degeneracy lifting of LLs implies the presence of a gap between the conduction and valence bands of graphene, which is in general present in experimental conditions, although specific production techniques such as encapsulation with hexagonal boron nitride (hBN) [28,29] are able to produce high-purity graphene samples with essentially no gap.…”

“…The degeneracy lifting of LLs implies the presence of a gap between the conduction and valence bands of graphene, which is in general present in experimental conditions, although specific production techniques such as encapsulation with hexagonal boron nitride (hBN) [28,29] are able to produce high-purity graphene samples with essentially no gap. Very clean pn junctions in nanoribbons of monolayer graphene are then created, to study transport phenomena in the quantum Hall regime: among these, the coexistence between edge states and snake states along pn junctions [30][31][32][33][34][35][36][37][38][39], and the occurrence of Klein tunneling through electrostatic barriers [19,[39][40][41][42].…”