Realistic systems testing Klein tunneling in graphene: An ab initio calculations

We investigate the tunneling in monolayer graphene (MLG) through the potential barrier generated by the ribbons of Na, Cl and h-BN using the density functional theory (DFT) approach. Such an approach to the problem resulted in determining the shapes and parameters of the potential barriers in individual nanodevices in contrast to the tight binding (TB) approach where these parameters are assumed. In all systems we could observe the Klein tunneling features although under complex potential barrier/well profiles for some cases. The double barrier created in systems consisting of h-BN ribbons as overlayers/underlayers on graphene (h-BN/MLG/h-BN) allowed to analyze Klein tunnelling depending on the distance between two triangular barriers. The presented concept gives the possibility to measure the angular dependence of tunnelling and as such is of particular relevance to alternative/supplementary experiments to those related to observations of Klein tunnelling in graphene through potential barriers generated by applying a gate voltage.