Research progress of ultra-wide bandgap two-dimensional semiconductor materials and devices

As one of the frontiers in the field of two-dimensional materials research, ultra-wide bandgap two-dimensional (UWBG 2D) semiconductors, while following the development of the third and fourth generation semiconductors in the direction of large bandgap and high power, provide ideas for the exploration of integrated circuits towards small volume and high integration. According to whether the crystal stacking is a van der Waals layered structure, from the perspective of material, the research content of UWBG 2D semiconductors is aimed at obtaining ultra-thin film of the existed and mature nonlayered materials through versatile methods and exploring novel van der Waals layered materials to get the single layer or few layers by direct growth or exfoliation. From the perspective of device, the UWBG 2D semiconductors are mostly formed to detect electromagnetic waves in the ultraviolet solar-blind region, whether they are in an independent form or stacked in pairs to form a heterojunction. Furthermore, they can be completed with additional circuits and devices to become imaging system, digital communication equipment or other optical sensors. If assisted by a flexible substrate, 2D materials will take advantage of their natural bendability and be widely used in wearable electronic devices such as flexible field-effect transistors, flexible UV detectors, and displays. When the material has the property of "memory" to external stimuli (such as light), it means that the material can be used for neural-like synaptic sensing or neural network learning after training. In addition, some materials with extremely large bandgaps in UWBG 2D semiconductors are potential dielectrics. They often have a much larger dielectric constant and breakdown voltage than silicon dioxide, which can reduce the size of the device while improving the performance. Finally, a few UWBG 2D semiconductors are naturally good substrates in the preparation of many materials due to their easy availability and atomically clean surfaces, which provide the breeding ground for the birth of a variety of new materials, making them critical cornerstones in the field of 2D material.