物理化学学报 >> 2015, Vol. 31 >> Issue (6): 11911191-1198.doi: 10.3866/PKU.WHXB201504011

材料物理化学 上一篇    下一篇

La或N掺杂SiC纳米线的制备、场发射性能及第一性原理计算

李镇江1, 马凤麟1, 张猛1, 宋冠英1, 孟阿兰2   

  1. 1 青岛科技大学中德科技学院, 机电工程学院, 山东省高分子材料先进制造技术重点实验室, 山东青岛266061;
    2 青岛科技大学化学与分子工程学院, 生态化工国家重点实验室培育基地, 山东青岛266061
  • 收稿日期:2014-12-15 修回日期:2015-04-01 发布日期:2015-06-05
  • 通讯作者: 孟阿兰 E-mail:alanmengqust@163.com
  • 基金资助:

    国家自然科学基金(51272117, 51172115), 高等学校博士学科点专项科研基金(20123719110003), 山东省科技攻关项目基金(2012GGX10218)和青岛市应用基础研究计划项目(13-1-4-117-jch)资助

Preparation, Field Emission Characteristics and First-Principles Calculations of La-Doped or N-Doped SiC Nanowires

LI Zhen-Jiang1, MA Feng-Lin1, ZHANG Meng1, SONG Guan-Ying1, MENG A-Lan2   

  1. 1 Key Laboratory of Polymer Material Advanced Manufactorings Technology of Shandong Provincial, College of Chinesisch- Deutsche Technische Fakultat, College of Electromechanical Engineering, Qingdao University of Science and Technology, Qingdao 266061, Shandong Province, P. R. China;
    2 State Key Laboratory Base of Eco-chemical Engineering, College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, Qingdao 266061, Shandong Province, P. R. China
  • Received:2014-12-15 Revised:2015-04-01 Published:2015-06-05
  • Contact: MENG A-Lan E-mail:alanmengqust@163.com
  • Supported by:

    The project was supported by the National Natural Science Foundation of China (51272117, 51172115), Specialized Research Fund for the Doctoral Program of Higher Education of China (20123719110003), Tackling Key Program of Science and Technology in Shandong Province, China (2012GGX10218), and Application Foundation Research Program of Qingdao, China (13-1-4-117-jch).

摘要:

采用化学气相沉积法和气相掺杂法, 分别制备了La 或N掺杂的SiC 纳米线. 利用场发射扫描电子显微镜(FE-SEM)、透射电子显微镜(TEM)、选区电子衍射(SAED)、高分辨透射电子显微镜(HRTEM)、X射线能量色散谱(EDS)分析和X射线衍射(XRD)等测试手段对两种产物的微观形貌、元素组成和物相结构进行了系统表征. 以合成产物作为阴极, 对其场发射性能进行测试, 结果表明: SiC 纳米线的开启电场值和阈值电场值由未掺杂的2.3、6.6 V·μm-1分别降低为1.2、5.2 V·μm-1(La 掺杂)和0.9、0.4 V·μm-1(N 掺杂). 采用Material Studio 软件中的Castep 模块建立(3×3×2)晶格结构模型, 对未掺杂、La 或N掺杂SiC 的能带结构和态密度进行计算, 结果显示: La或N掺杂后, 在费米能级附近产生了新的La 5d或N 2p掺杂能级, 导致禁带宽度(带隙)变窄, 使得价带电子更容易跨越禁带进入导带, 从而改善SiC纳米线的场发射性能.

关键词: 场发射性能, La掺杂, N掺杂, SiC纳米线, 第一性原理

Abstract:

La- and N-doped SiC nanowires were prepared using a vapor-phase doping method and chemical vapor deposition method, respectively. The morphologies, element analysis, and crystal structures of the products were characterized by field emission scanning electron microscope (FE-SEM), transmission electron microscope (TEM), selected area electron diffraction (SAED), high-resolution transmission electron microscope (HRTEM), X-ray energy dispersive spectrum (EDS), and X-ray diffraction (XRD). The field emission properties of the nanowires doped with different elements were tested by field emission measurements, and the results show that the turn on field (Eto) and threshold field (Ethr) of La-doped SiC nanowires are 1.2 and 5.2 V·μm-1, and those of N-doped SiC nanowires are 0.9 and 4.0 V·μm-1, respectively, these values are clearly lower than those of 2.3 and 6.6 V·μm-1 for undoped SiC nanowires. In addition, the density of states (DOS) and band structures of undoped, N-doped, and La-doped, SiC nanowires were also calculated using Castep of material studio on the basis of the first-principles. The results of the theoretical calculations suggest that the narrower gap may be attributed to the impurity energy level (La 5d or N 2p) generated near the Fermi level. Because of the narrower gap, electrons transfer from the valence band maximum (VBM) to conduction band minimum (CBM) need less energy, and this enhances the field emission property.

Key words: Field emission property, La-doping, N-doping, SiC nanowire, First-principles

MSC2000: 

  • O649