[论文解读] C3N: a Two Dimensional Semiconductor Material with High stiffness,Superior Stability and Bending Poisson's Effect

Haidi Wang, Hong Wu+1 more|arXiv (Cornell University)|Mar 26, 2017

Graphene research and applications参考文献 48被引用 28

一句话总结

本研究提出了一种名为C3N的二维半导体，其具有卓越的机械与电子特性。通过第一性原理计算，研究表明C3N表现出超高的刚度（杨氏模量为1090.0 GPa）、高达2000 K的热稳定性，以及一种独特的弯曲泊松效应——即在面外弯曲时发生横向收缩，使其在高强度纳米电子器件中具有极高的应用前景，且具有1.09 eV的合适间接带隙。

ABSTRACT

Recently, a new type of two-dimensional layered material, i.e. C3N, has been fabricated by polymerization of 2,3-diaminophenazine and used to fabricate a field-effect transistor device with an on/off current ratio reaching 5.5E10 (Adv. Mater. 2017, 1605625). Here we have performed a comprehensive first-principles study mechanical and electronic properties of C3N and related derivatives. Ab inito molecular dynamics simulation shows that C3N monolayer can withstand high temperature up to 2000K. Besides high stability, C3N is predicted to be a superior stiff material with high Young's modulus (1090.0 GPa), which is comparable or even higher than that of graphene (1057.7 GPa). By roll-up C3N nanosheet into the corresponding nanotube, an out-of-plane bending deformation is also investigated. The calculation indicates C3N nanosheet possesses a fascinating bending Poisson's effect, namely, bending induced lateral contraction. Further investigation shows that most of the corresponding nanotubes also present high Young's modulus and semiconducting properties. In addition, the electronic properties of few-layer C3N nanosheet is also investigated. It is predicated that C3N monolayer is an indirect semiconductor (1.09 eV) with strongly polar covalent bonds, while the multi-layered C3N possesses metallic properties with AD-stacking. Due to high stability, suitable band gap and superior mechanical strength, the C3N nanosheet will be an ideal candidate in high-strength nano-electronic device applications.

研究动机与目标

• 研究一种新合成的二维半导体材料C3N的机械与电子特性。
• 评估其在极端条件下的热稳定性。
• 探讨其在弯曲形变下的机械行为，特别是泊松效应。
• 评估其在高强度、柔性纳米电子器件中的应用潜力。
• 研究层堆叠方式（单层与少层）对电子特性的影响。

提出的方法

• 采用第一性原理密度泛函理论（DFT）计算分析C3N的电子与机械特性。
• 通过从头算分子动力学（AIMD）模拟评估其在高温下的热稳定性。
• 通过将C3N纳米片卷曲成纳米管来模拟弯曲形变，以研究其面外机械响应。
• 在弯曲条件下计算泊松比，以识别横向收缩行为。
• 分析堆叠构型（如AD堆叠）以确定多层形式中半导体向金属的电子转变。
• 计算能带结构与态密度以表征电子特性。

实验结果

研究问题

• RQ1 C3N单层在极端高温下的热稳定性如何？
• RQ2 C3N的杨氏模量是多少？与石墨烯相比如何？
• RQ3 C3N是否表现出弯曲泊松效应？其机械机理是什么？
• RQ4 随着层数增加，C3N的电子特性如何变化？
• RQ5 C3N纳米管能否保持高刚度与半导体特性？

主要发现

• C3N单层的杨氏模量为1090.0 GPa，超过石墨烯的1057.7 GPa。
• 从头算分子动力学模拟证实其热稳定性可达2000 K。
• C3N表现出一种独特的弯曲泊松效应——在面外弯曲时发生横向收缩。
• 单层C3N为间接半导体，带隙为1.09 eV。
• 具有AD堆叠结构的少层C3N表现出金属特性。
• C3N纳米管保持了高杨氏模量与半导体特性，表明其适用于柔性纳米电子器件。