Tang Shuai, Tang Jie, Chiu Ta-Wei, Uzuhashi Jun, Tang Dai-Ming, Ohkubo Tadakatsu, Mitome Masanori, Uesugi Fumihiko, Takeguchi Masaki, Qin Lu-Chang
National Institute for Materials Science, Tsukuba, Ibaraki 305-0047, Japan.
Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3255, USA.
Nanoscale. 2020 Aug 20;12(32):16770-16774. doi: 10.1039/d0nr03406a.
A single hafnium carbide (HfC) nanowire field-induced electron emitter with a sharp tip apex is fabricated by Pt deposition and focused ion beam (FIB) milling. The structure of the electron emitter is characterized by scanning transmission electron microscopy (STEM) and atom probe tomography (APT). The HfC nanowire is single-crystalline with a thin oxide layer on its tip surface. The field emission properties are determined by using both in situ transmission electron microscopy (TEM) and a field-emission probe in a high-vacuum chamber. A high current of 173 nA was obtained at a low extraction voltage of 631 V with an emission gap of 5 mm. The emission current is stable at 60 nA for 100 min with a fluctuation of 0.7%. The deduced work function was 3.1 eV. It is suggested that the implanted Ga ions and the oxide layer induce more downward dipoles that are beneficial for lowering the work function and creating a stable surface. When the low keV FIB processing is applied, it takes within 30 minutes to finish a HfC nanowire emitter, establishing an efficient procedure for the preparation of nanowire emitters. These results provide a controllable and fast production method for the fabrication of single nanowire field-emission point electron sources.
通过铂沉积和聚焦离子束（FIB）铣削制备了一种具有尖锐顶端的单根碳化铪（HfC）纳米线场致电子发射器。利用扫描透射电子显微镜（STEM）和原子探针断层扫描（APT）对电子发射器的结构进行了表征。HfC纳米线为单晶，其顶端表面有一层薄氧化层。通过原位透射电子显微镜（TEM）和高真空腔中的场发射探针来测定场发射特性。在631 V的低提取电压和5 mm的发射间隙下，获得了173 nA的高电流。发射电流在60 nA下稳定100分钟，波动为0.7%。推导得到的功函数为3.1 eV。研究表明，注入的Ga离子和氧化层会诱导更多向下的偶极子，这有利于降低功函数并形成稳定的表面。当采用低keV FIB工艺时，制备一根HfC纳米线发射器只需30分钟以内，从而建立了一种制备纳米线发射器的高效方法。这些结果为单纳米线场发射点电子源的制造提供了一种可控且快速的生产方法。
