Integration of Two-dimensional Materials with Functional Dielectrics

• Applicant: Dr.-Ing. Alexander Henning, Ph.D.
• Subject Area: Microsystems ; Electrical Energy Systems, Power Management, Power Electronics, Electrical Machines and Drives ; Electronic Semiconductors, Components and Circuits, Integrated Systems, Sensor Technology, Theoretical Electrical Engineering ; Synthesis and Properties of Functional Materials ; Physical Chemistry of Solids and Surfaces, Material Characterisation
• Term: from 2017 to 2018
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 386647094

Two-dimensional (2D) van der Waals (vdW) materials encompass compounds such as graphene, boron nitride and black phosphorous (BP), as well as transition metal dichalcogenides (TMDs) such as MoS2 and WS2, which are ranked as the most promising materials to augment or replace standard silicon technology that reaches its fundamental physical limits around 2020. Despite enormous efforts in recent years, several challenges need to be addressed to make these materials a viable platform for technology. For example integration of 2D materials with dielectrics remains a key challenge. The famous phrase "the interface is the device" is perfectly true for 2D materials. The goal of the proposed research is to enable device functionality by integration of 2D material with dielectrics in such a way that the intrinsic properties of the vdW semiconductor are largely preserved. Our objective is to develop dielectric growth strategies that will not only mitigate the influence of defects to provide greater control of the Fermi level in 2D-material-based devices, but will also effect charge transfer doping to provide a foundation for integration into new types of homo- and heterojunction devices.The research will include charge transfer doping of vdW materials with a well-controlled growth of dielectric layers by means of atomic layer deposition (ALD) at low temperatures. Novel p-n junctions will be created with two different dielectric layers in contact with the vdW materials. The influence of dielectric adlayers on the electronic properties of combined vdW semiconductor/dielectric junctions will be quantified from electrical device characteristics. Klvin probe force microscopy will be used to determine the density of interface states and characterize the space charge regions of vdW-material-based devices integrated with different dielectrics. This knowledge is important to effectively integrate vdW materials with different dielectrics and semiconductors, and to establish a foundation for device engineering. The proposed research will accelerate the development of 2D-materials-based devices for applications beyond the research lab.

• DFG Programme: Research Fellowships
• International Connection: USA
• Host: Professor Lincoln Lauhon, Ph.D.