Needle-Shaped Single-Crystalline Molybdenum Micro-Nano Structure with High Conductivity and Excellent Field Emission Properties: Implications for Large-Current Cold-Cathodes

• Published in: ACS applied nano materials Vol. 6; no. 13; pp. 12486 - 12496
• Main Authors: Cheng, Ao, Shen, Yan, Cui, Tao, Feng, Wenyong, Zhan, Runze, Pei, Yanli, Tang, Shuai, Chen, Huanjun, Deng, Shaozhi
• Format: Journal Article
• Language: English
• Published: American Chemical Society 14.07.2023
• Subjects: high-conductivity; needle-shaped molybdenum structure; large emission current; high-quality single crystal; field emission cold-cathode
• ISSN: 2574-0970; 2574-0970
• DOI: 10.1021/acsanm.3c02241

High-melting point metallic micro-nano structural materials are well recognized as good conductors and electron emitters, particularly in the field of cold-cathode electron source and vacuum electron device applications. Developing their single-crystalline structures helps to further obtain large-current and high-power output performance; however, the controllable preparation of materials is always a difficult problem. In this study, we successfully realized the controllable self-assembled growth of high-quality needle-shaped molybdenum (Mo) micro-nano structures, by developing a modified thermal vapor deposition method. The Mo needle typically exhibits ultralong quasi-one dimension (up to ∼1.5 mm) and a sharp tip-end, with a perfect single-crystalline nature. Based on this structural feature, a type of Mo individual with a continuous structure is demonstrated to show an excellent conductivity of approximately 5 × 105 Ω–1 cm–1 and very large field emission current up to 93.1 μA with a corresponding current density of 1.2 × 105 A cm–2, standing out from most of the reported cold-cathode nanomaterials. This study provides a potential cold-cathode material with high conductivity and large current for vacuum electronic applications and also indicates a feasible path to achieve the preparation of high-quality single crystals of high-melting-point metals.