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arXiv 2105.03334cond-mat.mtrl-sciphysics.app-ph
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分子束外延PtSe $_2$的精确电子结构

Precise Layer-Dependent Electronic Structure of MBE-Grown PtSe$_2$

Lei Zhang, Tong Yang, Muhammad Fauzi Sahdan, Arramel, Wenshuo Xu, Kaijian Xing, Yuan Ping Feng, Wenjing Zhang, Zhuo Wang, Andrew T. S. Wee

摘要:

二维(2D)二硒化铂(PtSe $_2$)由于其高迁移率而在2D晶体管应用中受到极大关注。在这里,使用分子束外延,我们研究了二维PtSe $_2$的高度取向热解石墨(HOPG)的生长,并通过X射线光电子能谱学,拉曼光谱,扫描隧道显微镜/光谱以及密度泛函理论(DFT)计算揭示其电子性质。PtSe $_2$在HOPG上采用逐层生长的方式生长,禁带宽度随着层数的增加而减小。对于层数从1到4,PtSe $_2$分别具有$2.0 \pm 0.1$、$1.1 \pm 0.1$、$0.6 \pm 0.1$和$0.20 \pm 0.1$ eV的带隙,并且从第五层开始变为半金属。DFT计算再现层依赖的带隙和带边的演化,提出了一个间接的带隙结构,并阐明了在原子水平上的基本物理。

英文摘要:

Two-dimensional (2D) platinum diselenide (PtSe$_2$) has received significant attention for 2D transistor applications due to its high mobility. Here, using molecular beam epitaxy, we investigate the growth of 2D PtSe$_2$ on highly oriented pyrolytic graphite (HOPG) and unveil their electronic properties via X-ray photoelectron spectroscopy, Raman spectra, and scanning tunnelling microscopy/spectroscopy as well as density functional theory (DFT) calculations. PtSe$_2$ adopts a layer-by-layer growth mode on HOPG and shows a decreasing band gap with increasing layer number. For the layer numbers from one to four, PtSe$_2$ has band gaps of $2.0 \pm 0.1$, $1.1 \pm 0.1$, $0.6 \pm 0.1$ and $0.20 \pm 0.1$ eV, respectively, and becomes semimetal from the fifth layer. DFT calculations reproduce the layer-dependent evolution of both the band gap and band edges, suggest an indirect band-gap structure, and elucidate the underlying physics at the atomic level.

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