Search for: All records

Abstract Epitaxy, a process to prepare crystalline materials in nanostructures and thin films, is the core technology for preparing high‐quality materials as a key enabler of next‐generation microelectronics and quantum information system. Progress in epitaxy has been expanding the choice of materials and their heterostructures beyond the combinations limited by materials compatibility. However, the improvement of material quality, physical implementation of materials with unique properties, and integration of incommensurate materials in an architecture have been the challenging issues. Emerging materials, including 2D materials and quantum materials, have opened opportunities to study epitaxy mechanisms and realize various functional devices. Acceleration of discovery and progress in epitaxy research should be accomplished by “understanding of epitaxy under various circumstances at multiple length scales” and “integration of experiments and models.” In the perspective, a basic summary of the status of epitaxially grown materials, the challenges in epitaxy research, and integration of modeling epitaxy and ultimate control of the epitaxy process with advanced characterization techniques are discussed. 

The concept of remote epitaxy involves a two-dimensional van der Waals layer covering the substrate surface, which still enable adatoms to follow the atomic motif of the underlying substrate. The mode of growth must be carefully defined as defects, e.g., pinholes, in two-dimensional materials can allow direct epitaxy from the substrate, which, in combination with lateral epitaxial overgrowth, could also form an epilayer. Here, we show several unique cases that can only be observed for remote epitaxy, distinguishable from other two-dimensional material-based epitaxy mechanisms. We first grow BaTiO₃on patterned graphene to establish a condition for minimizing epitaxial lateral overgrowth. By observing entire nanometer-scale nuclei grown aligned to the substrate on pinhole-free graphene confirmed by high-resolution scanning transmission electron microscopy, we visually confirm that remote epitaxy is operative at the atomic scale. Macroscopically, we also show variations in the density of GaN microcrystal arrays that depend on the ionicity of substrates and the number of graphene layers. 

Abstract Wide‐bandgap semiconductors (WBGs) are crucial building blocks of many modern electronic devices. However, there is significant room for improving the crystal quality, available choice of materials/heterostructures, scalability, and cost‐effectiveness of WBGs. In this regard, utilizing layered 2D materials in conjunction with WBG is emerging as a promising solution. This review presents recent advancements in the integration of WBGs and 2D materials, including fabrication techniques, mechanisms, devices, and novel functionalities. The properties of various WBGs and 2D materials, their integration techniques including epitaxial and nonepitaxial growth methods as well as transfer techniques, along with their advantages and challenges, are discussed. Additionally, devices and applications based on the WBG/2D heterostructures are introduced. Distinctive advantages of merging 2D materials with WBGs are described in detail, along with perspectives on strategies to overcome current challenges and unlock the unexplored potential of WBG/2D heterostructures.