Van der Waals heterostructure based self-switching diode

The aim of this project is to design and develop a novel nanoelectronic rectifier, also known as self-switching diode (SSD), from van der Waals hetrostructure consisting of graphene/h-BN/MoS2 layers. Due to excellent material properties, proposed SSDs can operate with ultra-fast switching speed than that of electronic rectifiers fabricated from conventional semiconductors for a wide variety of applications such as signal detection, future generation communications, medical and security imaging etc. Recently, emerging two-dimensional (2D)-layered semiconductors including graphene, hexagonal boron nitride (h-BN) and molybdenum disulphide (MoS2) have shown considerable potential for designing next-generation integrated electronic and optoelectronic devices, due to their excellent unique physical and structural properties. Particularly, the 2D-layered semiconductors of graphene, h-BN and MoS2 can be flexibly combined to form different configurations of vertical van der Waals heterostructures with atomically sharp interfaces and tunable band alignment, opening up vast opportunities for fundamental investigation of novel electronic properties at the limit of single atom thickness and potential applications in novel devices concept such as self-switching diode. The working of conventional rectifying diodes depend either upon a pn doped junction or a Schottky barrier, that also determines the limitations. An applied bias high enough is generally required to overcome the built-in electric field and to allow a significant current flow, introducing the parasitic capacitance which in turn limits the operating speed and high frequency performance. The novel nanodiode concept proposed in this project is entirely different and it has a single‐layered device architecture that is ideally‐suited to graphene and/or graphene based van der Waals heterostructures. Moreover, it operates on new working principle enabling zero threshold voltage, thus eliminating the need for a bias circuit. Developing SSD in graphene/h-BN/MoS2 is timely given the rapid progress in graphene and/or 2d van der Waals material engineering. Since the device speed generally scales with the carrier mobility, the proposed SSDs are expected to operate at very high frequencies possibly up to THz.