Stacking and electric field effects on the electronic properties of the layered GaN

Stability and electronic properties of atomic layers of GaN are investigated in the framework of the van der Waals-density functional theory. We find that the ground state of the layered GaN is a planar graphene-like configuration rather than a buckled bulk-like configuration. Application of an external perpendicular electric field to the layered GaN induces distinct stacking-dependent features of the tunability of the band gap; the band gap of the monolayer does not change whereas that of the trilayer GaN is significantly reduced for the applied field of 0.4 V/ {AA}. It is suggested that such a stacking-dependent tunability of the band gap in the presence of an applied field may lead to novel applications of the devices based on the layered GaN.

Disorder induced field effect transistor in bilayer and trilayer graphene

We propose use of disorder to produce a field effect transistor (FET) in biased bilayer and trilayer graphene. Modulation of the bias voltage can produce large variations in the conductance when the disorders effects are confined to only one of the graphene layers. This effect is based on the bias voltages ability to select which of the graphene layers carries current, and is not tied to the presence of a gap in the density of states. In particular, we demonstrate this effect in models of gapless ABA-stacked trilayer graphene, gapped ABC-stacked trilayer graphene, and gapped bilayer graphene.