Multilayer transistors based on graphene and other van der Waals crystals [1-8] exhibit many interesting physical properties: high on-off current switching ratios, mechanical flexibility, photoresponsivity, light emission, and resonant tunnelling with gate voltage-tuneable negative differential conductance at room temperature. Here, I will give a brief review of our recent work on electron tunneling between the graphene layers of these devices. I will demonstrate the strong sensitivity of in-plane momentum conserving tunnel transitions to any small misalignment or twist angle between the crystalline lattices of the two graphene electrodes [3-5]. For devices where there is a large misalignment between the graphene lattices, I will show how phonon emission can determine the tunnel current [6]. Finally, I will explain how an applied magnetic field can be used to reveal the effects of chirality, which is a unique feature of electron dynamics in graphene and related materials [7,8].

[1] K.N. Novoselov et al., Science 353, 461 (2016).

[2] T. Georgiou et al., Nat. Nanotechnol. 2, 100 (2013).

[3] L. Britnell et al., Nat. Commun. 4, 1794 (2013).

[4] A. Mishchenko et al., Nat. Nanotechnol. 9, 808 (2014).
[5] J. Gaskell et al., Appl. Phys. Lett. 107, 103105 (2015).
[6] E.E. Vdovin et al., Phys. Rev. Lett., 116, 186603 (2016).

[7] M.T. Greenaway et al., Nat. Phys. 11, 1057 (2015).
[8] J.R. Wallbank et al., Science 353, 575 (2016).