Highly efficient spin field-effect transistor based on nanographene and hBN heterostructures: spintronic and quantum transport properties

Intense efforts are being undertaken to design atomic-scale nanodevices in response to the demand for novel electronic/spintronic devices to address the problems facing the current devices. In this work, we construct new spintronic nanodevices based on 2D heterostructures from graphene and hBN quantum dots. The heterostructures are ferromagnetic spin-ordered semiconductors with nonzero spin originating from the unpaired edge electrons of the graphene quantum dots. The net spin and its distribution on different layers of the heterostructures are controllable. For instance, doping the hBN layer in the lateral graphene-hBN-graphene structure with C-atoms can boost the net spin and facilitate its distribution on the three layers. The electronic properties are also affected where half metallicity has been achieved in this system. The I-V characteristics of the lateral G-hBN heterostructure show an oscillating spin-up current that is significantly higher than the regular spin-down current. Doping G-hBN with C-atoms significantly enhances the current magnitude and removes the oscillation due to the decreased net spin by the dopants. We demonstrate a field effect transistor from the lateral G-hBN-G heterostructure that operates based on quantum tunneling from the G-layer through the hBN-layer. The device works as a spin filter at zero gate voltage. A significant enhancement of the drain current is achieved by applying a positive gate voltage. This device shows an ON/OFF ratio of up to 1010 making it an ideal applicant for future spintronic nanodevices.