Institute for Materials Research (IMO), Hasselt University, 3590 Diepenbeek, Belgium.
Nanoscale. 2018 Jan 18;10(3):1345-1355. doi: 10.1039/c7nr06774g.
Carbon nanomaterials such as nanotubes, nanoflakes/nanowalls, and graphene have been used as electron sources due to their superior field electron emission (FEE) characteristics. However, these materials show poor stability and short lifetimes, which prevent their use in practical device applications. The aim of this study was to find an innovative nanomaterial possessing both high robustness and reliable FEE behavior. Herein, a hybrid structure of self-organized multi-layered graphene (MLG)-boron doped diamond (BDD) nanowall materials with superior FEE characteristics was successfully synthesized using a microwave plasma enhanced chemical vapor deposition process. Transmission electron microscopy reveals that the as-prepared carbon clusters have a uniform, dense, and sharp nanowall morphology with sp diamond cores encased by an sp MLG shell. Detailed nanoscale investigations conducted using peak force-controlled tunneling atomic force microscopy show that each of the core-shell structured carbon cluster fields emits electrons equally well. The MLG-BDD nanowall materials show a low turn-on field of 2.4 V μm, a high emission current density of 4.2 mA cm at an applied field of 4.0 V μm, a large field enhancement factor of 4500, and prominently high lifetime stability (lasting for 700 min), which demonstrate the superiority of these materials over other hybrid nanostructured materials. The potential of these MLG-BDD hybrid nanowall materials in practical device applications was further illustrated by the plasma illumination behavior of a microplasma device with these materials as the cathode, where a low threshold voltage of 330 V (low threshold field of 330 V mm) and long plasma stability of 358 min were demonstrated. The fabrication of these hybrid nanowalls is straight forward and thereby opens up a pathway for the advancement of next-generation cathode materials for high brightness electron emission and microplasma-based display devices.
碳纳米材料，如纳米管、纳米片/纳米墙和石墨烯，因其具有优异的场致电子发射（FEE）特性而被用作电子源。然而，这些材料表现出较差的稳定性和较短的寿命，这阻止了它们在实际设备应用中的使用。本研究的目的是找到一种具有高稳定性和可靠的 FEE 行为的创新纳米材料。在此，使用微波等离子体增强化学气相沉积工艺成功合成了具有优异 FEE 特性的自组织多层石墨烯（MLG）-掺硼金刚石（BDD）纳米墙材料的混合结构。透射电子显微镜显示，所制备的碳团簇具有均匀、致密和尖锐的纳米墙形态，具有 sp 金刚石核和 sp MLG 壳。使用峰值力控制隧道原子力显微镜进行的详细纳米尺度研究表明，每个核壳结构的碳团簇场都能均匀地发射电子。MLG-BDD 纳米墙材料表现出低的开启场为 2.4 V μm，在 4.0 V μm 的外加电场下，发射电流密度高达 4.2 mA cm，场增强因子高达 4500，并且具有突出的长寿命稳定性（持续 700 分钟），这表明这些材料优于其他混合纳米结构材料。通过使用这些材料作为阴极的微等离子体装置的等离子体照明行为进一步说明了这些 MLG-BDD 混合纳米墙材料在实际设备应用中的潜力，其中显示出低阈值电压 330 V（低阈值场 330 V mm）和长等离子体稳定性 358 分钟。这些混合纳米墙的制造简单直接，为下一代用于高亮度电子发射和基于微等离子体的显示器件的阴极材料的发展开辟了道路。
