by Researchers from Hunan University, the Chinese Academy of Sciences, and Wuhan University have successfully developed new transistors using monolayer semiconducting materials, black phosphorus (BP), and germanium arsenide (GeAs). The study, published in the journal Nature Electronics, aims to explore alternative 2D semiconducting materials for the creation of monolayer transistors. These materials have significant advantages over their bulk counterparts, such as retained carrier mobility despite their reduced thickness.
While 2D semiconductors offer great promise for creating thin electronics, monolayer transistors using these materials are still relatively rare. Most monolayer transistors are based on carefully selected materials like graphene, tungsten diselenide, or molybdenum disulfide. The researchers sought to overcome this limitation by using other 2D semiconducting materials primarily used for multi-layer transistors, namely BP and GeAs.
The fabrication of monolayer transistors using materials like BP and GeAs presents challenges due to the difficulties in forming stable electrical contacts with delicate 2D materials. To address this issue, the researchers developed a van der Waals peeling technique, which involves laminating flat metals onto multilayer 2D channels. This technique allows for the removal of the semiconducting layer at the top of the stack by peeling off the metal.
By gradually reducing the channel region of a multilayer BP transistor to monolayer thickness through mechanical peeling, the researchers were able to maintain the delicate lattice structure while retaining a multilayer contact region. The team used their proposed peeling technique to create homo-junctions and homo-superlattices based on various 2D semiconductors, including BP, GeAs, InSe, and GaSe.
The researchers found that their method enabled them to thin down the channel part of the transistors while maintaining the necessary thickness in the contact region. The study also revealed that the carrier mobility of black phosphorus decreased sharply when reducing the body thickness, behaving more like a conventional bulk semiconductor rather than a pure van der Waals semiconductor.
The team demonstrated the potential of their technique for developing monolayer transistors with 3D-raised contacts using BP and GeAs. In the future, this layer-by-layer peeling method could pave the way for the creation of thinner and scalable transistors using unconventional 2D semiconductors that are typically considered poorly performing for these applications.
The implications of this work extend beyond 2D semiconductors to other unstable monolayer materials, such as organic monolayers and perovskite monolayers. These materials, which were previously believed to be non-conductive or have poor intrinsic properties, can benefit from improved contact between metal and monolayers.
The development of transistors based on monolayer black phosphorus and germanium arsenide offers exciting possibilities for the advancement of electronic devices. The unique properties of these materials, combined with the novel van der Waals peeling technique, open up new opportunities for creating thinner and more scalable transistors. This research not only expands the range of materials suitable for monolayer transistor design but also has implications for other unstable monolayer materials in various applications.
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1. Source: Coherent Market Insights, Public sources, Desk research
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