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2D native surface oxides formed on low melting temperature metals such as indium and gallium offer unique opportunities for fabricating high-performance flexible electronics and optoelectronics based on a new class of liquid metal printing (LMP). An inherent property of these Cabrera-Mott 2D oxides is their suboxide nature (e.g., In2O3−x), which leads high mobility LMP semiconductors to exhibit high electron concentrations (ne > 1019 cm−3) limiting electrostatic control. Binary alloying of the molten precursor can produce doped, ternary metal oxides such as In-X-O with enhanced electronic performance and greater bias-stress stability, though this approach demands a deeper understanding of the native oxides of alloys. This work presents an approach for hypoeutectic rapid LMP of crystalline InGaOx (IGO) at ultralow process temperatures (180 °C) beyond the state of the art to fabricate transistors with 10X steeper subthreshold slope and high mobility (≈18 cm2 Vs−1). Detailed characterization of IGO crystallinity, composition, and morphology, as well as measurements of its electronic density of states (DOS), show the impact of Ga-doping and reveal the limits of doping induced amorphization from hypoeutectic precursors. The ultralow process temperatures and compatibility with high-k Al2O3 dielectrics shown here indicate potential for 2D IGO to drive low-power flexible transparent electronics.
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2D Amorphous Homojunction Transistors Exfoliated from Liquid Metals
Abstract Ultrathin 2D metal oxides are a high‐performance class of transparent conducting materials capable of overcoming the traditional limitations of inorganic flexible electronics. The low temperature, thermodynamically favorable synthesis of 2D oxides at liquid metal interfaces offers the potential for printing these materials over large areas at unprecedented speeds with sub‐nanometer scale precision. However, these native oxides are sub‐stoichiometric and highly conductive, so new strategies are needed that can precisely engineer the electrostatics and enhance stability. In this work, the crystalline vs. amorphous phase of 2D oxides is engineered via alloying of ternary In1‐ySnyOxand ultralow deposition temperatures (120–160 °C) are afforded by In‐Sn eutectics. This approach is extended to rapid assembly of nanoscale (3–5 nm per layer) vertical 2D homojunctions with electrostatically favorable grading from high density of states front channels to lower density of states back‐channels. Detailed materials characterization reveals how this platform enhances electron mobility while improving resilience under bias‐stress in metal oxide transistors. Devices based on amorphous 2D oxide homojunctions with high‐k sol‐gel ZrOxdielectrics achieve excellent electron mobility (30 cm2/V·s), steep switching (SS of 100 mV dec−1), Ion/offof 107and 10X reduced bias‐stress shifts, presenting an ideal strategy for high‐performance flexible oxide electronics.
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- PAR ID:
- 10652389
- Publisher / Repository:
- Wiley
- Date Published:
- Journal Name:
- Advanced Functional Materials
- ISSN:
- 1616-301X
- Page Range / eLocation ID:
- e12590
- Subject(s) / Keyword(s):
- liquid metals, 2D oxides, amorphous oxide semiconductors, oxide electronics, printed transistors
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript
- Journal Article:
- https://doi.org/10.1002/adfm.202512590
