二硒化铌的纳米级相工程,Chemistry of Materials

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二硒化铌的纳米级相工程
Chemistry of Materials ( IF 7.2 ) Pub Date : 2017-11-20 00:00:00 , DOI: 10.1021/acs.chemmater.7b03061
Felix Bischoff ₁ , Willi Auwärter ₁ , Johannes V. Barth ₁ , Agustin Schiffrin _{2,

3,

4} , Michael Fuhrer _{2,

3,

4} , Bent Weber _{2,

3,

4,

5}

Affiliation

随着半导体微电子学的不断小型化，原子薄材料正在成为未来超大规模电子学的有前途的候选材料。尤其是，层状过渡金属二硫化碳（TMDs）由于其电子性能的多样性而受到了广泛的关注，这取决于过渡金属的类型及其在晶体中的配位。在这里，我们使用低温扫描隧道显微镜（STM）对V TMD二硒化铌（NbSe ₂）。通过施加带有STM尖端的电压脉冲，我们可以将材料的晶体相局部地从三棱柱形（2H）转换为八面体（1T），这伴随着特征（√13×√13）R13.9°电荷的出现而得到证实。密度波（CDW）阶。在77 K处，具有亚晶格细节的结的原子分辨率STM图像证实了材料的成功相工程化，因为我们解决了顶部Se平面滑移所证明的Nb配位差异。不同的1T-CDW强度表明在1T-NbSe _2中存在层间相互作用。此外，明显的电压依赖性表明，复杂的CDW机制不像其他1T-TMD那样仅依赖于大卫之星的重建。此外，偏压脉冲会引起表面改性，从而引起局部晶格应变，从而对2H-NbSe ₂在4.5 K时的固有3×3 CDW有利于一维电荷顺序，而STM可逆地对其进行操纵。

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Nanoscale Phase Engineering of Niobium Diselenide

With the continuing miniaturization of semiconductor microelectronics, atomically thin materials are emerging as promising candidate materials for future ultrascale electronics. In particular, the layered transition metal dichalcogenides (TMDs) have attracted a significant amount of attention because of the variety of their electronic properties, depending on the type of transition metal and its coordination within the crystal. Here, we use low-temperature scanning tunneling microscopy (STM) for the structural and electronic phase engineering of the group V TMD niobium diselenide (NbSe₂). By applying voltage pulses with an STM tip, we can transform the material crystal phase locally from trigonal prismatic (2H) to octahedral (1T), as confirmed by the concomitant emergence of a characteristic (√13 × √13)R13.9° charge density wave (CDW) order. At 77 K, atomic-resolution STM images of the junction with sublattice detail confirm the successful phase engineering of the material, as we resolve the difference in the Nb coordination evidenced by a slip of the top Se plane. Different 1T-CDW intensities suggest interlayer interactions to be present in 1T-NbSe₂. Furthermore, a distinct voltage dependence suggests a complex CDW mechanism that does not just rely on a star-of-David reconstruction as in the case of other 1T-TMDs. Additionally, bias pulses cause surface modifications inducing local lattice strain that favors a one-dimensional charge order over the intrinsic 3 × 3 CDW at 4.5 K for 2H-NbSe₂, which can be reversibly manipulated by STM.

更新日期：2017-11-21

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