Graphene p-n junctions for electron-optics devices

The p-n junction is the building block for nearly all modern semiconductor devices, including transistors, Lasers, and LEDs. The absence of band gap in graphene, however, prevents the construction of same types of devices with graphene p-n junctions. Instead, graphene junctions are predicted to form a new class of electronic devices that have no analogue in modern electronics. Instead of turning on and off the flow of carriers, as in modern electronic devices, graphene junctions are predicted to manipulate carriers in the same way photons are guided in optics. These devices rely on the unique angle-dependent transport properties of graphene junctions. Unlike in bulk junctions, the transport in graphene junctions has a strong dependence on the transverse momentum of incident carriers. This gives rise to an angle dependence which can enable `electron optics´ devices. A number of such devices have been proposed that manipulate carriers in much the same way photons are guided in optics. They include the Veselago device, wave guiding structures, and steep subthreshold slope devices. These devices require the construction of graphene p-n junctions, because the junction can function as a dielectric discontinuity for carriers and can create either a negative or positive index of refraction. To that end, experimental verification of this angle-dependent transmission in graphene p-n junctions is provided herein.