Nitrogen content and morphology dependent field emission properties of nitrogen-doped SiC nanowires and density functional calculations.
Nitrogen content and morphology dependent field emission properties of nitrogen-doped SiC nanowires and density functional calculations.
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DOI：
10.1039/c5cp04064g
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发表时间：
2015-10
期刊：
影响因子：
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通讯作者：
Jian Zhao;A. Meng;Meng Zhang;W. Ren;Zhenjiang Li
中科院分区：
文献类型：
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作者：
Jian Zhao;A. Meng;Meng Zhang;W. Ren;Zhenjiang Li
以三聚氰胺为碳源和氮源，通过一步化学气相反应（CVR）合成了氮含量为0.975wt%~ 2.265wt%的氮掺杂SiC纳米线（N-doped SiC NW）。有趣的是，随着N掺杂量的增加，产物的形貌从轻微卷曲变为非常卷曲，并聚集在一起，这与所提出的SiC纳米线N掺杂生长模型相吻合。另外，电子结构计算结果表明，随着N含量的增加，禁带宽度逐渐变窄，场发射性能大大提高。然而，场发射测试结果表明，只有当N含量达到最佳值时，N掺杂SiC纳米线才能作为场发射体的候选材料，其开启场（E（to））为1.5 V μm（-1），阈值场（E（thr））为4 V μm（-1）。在此基础上，提出了一种普适的协同机制来解释N含量和形貌对N掺杂SiC纳米线FE性能的影响。
Nitrogen-doped SiC nanowires (N-doped SiC NWs) with a nitrogen content from 0.975 wt% to 2.265 wt% have been synthesized via a one-step chemical vapor reaction (CVR), where melamine served as both the carbon and nitrogen source. Interestingly, the morphology of the products changed from slightly curled to very curled with crowding together with the increase of N dopants, which was interpreted reasonably by the proposed N-doping growth model of SiC NWs. In addition, according to the electronic structure calculation results, the band gap is narrowed progressively with the increase of N content, which greatly enhances the field emission (FE) properties. However, the experimental results of the FE measurements substantiate that only when the N content takes an optimal value can the N-doped SiC NWs act as candidates for field emitters with very low turn-on fields (E(to)) of 1.5 V μm(-1) and threshold fields (E(thr)) of 4 V μm(-1). On the basis of the aforementioned phenomenon, a universal cooperativity mechanism was put forward to explain the effect of the N content and morphology on the FE properties of the N-doped SiC NWs.