The last decade has seen nearly exponential growth in the science and technology of two-dimensional materials.  Beyond graphene, there are a variety of layered materials that provide a broad range of electronic characteristics useful for transistors, flexible electronics, sensors, and photodetectors, to name a few. However, bridging the gap between science and technology often lies in one’s ability to synthesize materials on the wafer scale (or bigger). In this talk, I will discuss recent breakthroughs for direct growth of two-dimensional atomic layers and heterostructures with scalable techniques such as metal-organic chemical vapor deposition. We have demonstrated the direct growth of MoS2, WSe2, MoS2/WSe2, and hBN on epitaxial graphene to form large area van der Waals heterostructures. We reveal that the properties of the underlying substrate dictate properties of the layers and heterostructures, and that the direct synthesis of TMDs on epitaxial graphene exhibits atomically sharp interfaces. Our work has lead to a better understanding of vertical transport in 2D heterostructures, and we have identified new phenomenon in multi-junction heterostructures that has lead to resonance tunneling between layers and ultimately negative differential resistance. 

 

The last decade has seen nearly exponential growth in the science and technology of two-dimensional materials.  Beyond graphene, there are a variety of layered materials that provide a broad range of electronic characteristics useful for transistors, flexible electronics, sensors, and photodetectors, to name a few. However, bridging the gap between science and technology often lies in one’s ability to synthesize materials on the wafer scale (or bigger). In this talk, I will discuss recent breakthroughs for direct growth of two-dimensional atomic layers and heterostructures with scalable techniques such as metal-organic chemical vapor deposition. We have demonstrated the direct growth of MoS2, WSe2, MoS2/WSe2, and hBN on epitaxial graphene to form large area van der Waals heterostructures. We reveal that the properties of the underlying substrate dictate properties of the layers and heterostructures, and that the direct synthesis of TMDs on epitaxial graphene exhibits atomically sharp interfaces. Our work has lead to a better understanding of vertical transport in 2D heterostructures, and we have identified new phenomenon in multi-junction heterostructures that has lead to resonance tunneling between layers and ultimately negative differential resistance.