PDF《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》

[Article] www.

whxb.pku.edu.cn 物理化学学报(Wuli Huaxue Xuebao) Acta Phys. -Chim. Sin. 2015,

31 (6), 1191-1198 June Received: December 15, 2014;

Revised: April 1, 2015;

Published on Web: April 1, 2015. ? Corresponding author. Email: [email protected];

Tel: +86-13780601195. 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). 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 ? Editorial office of Acta Physico-Chimica Sinica doi: 10.3866/PKU.WHXB201504011 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 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) 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 中图分类号: O649 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 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) 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