全文下载：2013040336
孙莎莎， 李镇江*， 李伟东， 齐学礼
（青岛科技大学 机电工程学院， 山东 青岛 266061）
摘要： 利用简单的化学气相沉积法，首次以固态三聚氰胺(C3H6N6)为N掺杂剂，与Si/SiO2粉体混合，在1 250 ℃下保温25 min，制备出N掺杂SiC纳米线。采用XRD、SEM、元素分析等测试手段对产物的物相和微观形貌进行了表征，并对其场发射性能进行了研究，采用基于密度泛函理论（DFT）的第一性原理对N掺杂前后SiC纳米线的电子结构进行了计算。结果表明：掺N后的纳米线弯曲程度明显变大，场发射性能显著提高，开启电场值和阈值电场值由原来的3.5 V·μm-1和6.6 V·μm-1分别降低为2.6 V·μm-1和5.5 V·μm-1。此外，第一性原理计算表明，掺N后的纳米线禁带宽度明显变窄，使电子从价带向导带过渡时需要更少的能量，从理论上解释了N掺杂SiC纳米线场发射性能增强的原因。
关键词： SiC纳米线； 场发射； 第一性原理； 密度泛函理论
中图分类号： O 462.4； O 471.5 文献标志码： A
Preparation, Field Emission Property and First-principle Calculation on Electronic Structure of N-doped SiC Nanowires
SUN Sha-sha, LI Zhen-jiang, LI Wei-dong, QI Xue-li
(College of Electromechanical Engineering, Qingdao University of Science and Technology, Qingdao 266061，China)
Abstract: N-doped SiC nanowires were firstly preparated by chemical vapor reaction method, which used solid melamine(C3H6N6) as the N dopant, mixing with Si/SiO2 powders hearting 25 min at the temperature of 1 250 ℃. The crystal structure and morphology of the products were characterized by X-ray diffraction (XRD)、scanning electron microscopy (SEM) and element analysis. The field emission property of the products was also tested, and the electronic structures of un-doped and N-doped SiC nanowires were calculated via first-principle on the basis of the density functional theory (DFT). Results show that the bending degree of the N-doped SiC nanowires is bigger and it exhibits enhanced field emission activity comparing with the un-doped SiC nanowires, the turn-on field decreased from 3.5 V·μm-1 to 2.6 V·μm-1 and threshold field decreased from 6.6 V·μm-1 to 5.5 V·μm-1. The theoretical results indicate that calculated band gap of N-doped nanowires is narrower than that of un-doped samples and the transition of an electron from valence band to conduction band needs less energy which explained the reason of enhancement of field emission activity in theory.
Key words:SiC nanowires； field emission； first-principle calculations； density functional theory
收稿日期：2012-10-30
基金项目： 国家自然科学基金项目(51272117, 50972063)；山东省自然科学基金项目(ZR2011EMZ001,ZR2011EMQ011).
作者简介： 孙莎莎 (1987—)，女，硕士研究生.*通信联系人.
