In_(2)Se_(3)薄膜的掺杂效应及其纳米带铁电性

Doping effect and ferroelectricity of nanoribbons of In_(2)Se_(3)monolayer

低维材料的铁电性一直是凝聚态物理和材料科学领域的研究热点,在新型纳米电子器件的设计和应用等方面有重要的潜在应用和学术价值.本文基于密度泛函理论的第一性计算,以实验上已经验证的二维铁电材料In_(2)Se_(3)薄膜为出发点,研究了二维In_(2)Se_(3)薄膜的掺杂效应和In_(2)Se_(3)纳米带的铁电性.结果发现铁电性和金属性在静电掺杂的In_(2)Se_(3)薄膜中可以稳定共存,且电子掺杂会同时增强面内和面外极化,空穴掺杂可以增强面外极化,但抑制面内极化,从原子结构畸变和电子结构等角度详细解释了载流子掺杂对薄膜面内极化和面外极化的影响以及物理机制.针对In_(2)Se_(3)纳米带的研究,发现一维铁电性可以在In_(2)Se_(3)纳米线中存在,计算并给出了纳米带的局域极化分布和带隙,拟合了带隙和纳米带宽度之间满足E^(NR)_(G)-1/W^(2)标度关系.以期此研究可为拓宽二维铁电薄膜及其纳米结构的应用提供理论指导.

Ferroelectricity and nanostructure in low-dimensional material are a research hotspot in the condensed matter physics and material science,The low-dimensional material is significant for the application and desig of nano-electronic devices.Based on the density functional theory,the In_(2)Se_(3)monolayer,whose two-dimensional ferroelectricity has already been confirmed in experiment,is selected,and the ferroelectricity in the doped film and its nanoribbons are investigated.It is found that the ferroelectricity and the conductivity can coexist in the doped monolayer,and the electron doping enhances both the in-plane polarization(PIP)and the out-of-plane polarization(POOP),while the PIP is enhanced and POOP is depressed in the case of hole doping.The mechanism of the variation of polarization in the doped film is discussed on the basis of atomic distortions and electronic structures.As the In_(2)Se_(3)nanoribbons are concerned,the one-dimensional ferroelectricity can be found in the In_(2)Se_(3)nanowire,and the local polarization distribution within In_(2)Se_(3)nanoribbons and its band gap are calculated and discussed.Furthermore,the scaling law between the band gap and the width of nanoribbon is obtained by fitting the numerical results.It is expected that our study can broaden the application scope of 2D ferroelectric films and its nanostructures.