MoS2/In2Se3异质结电子结构与光电性质研究

Electronic Structure and Optoelectrical Properties of MoS2/In2Se3 Heterostructure

摘要:

二维材料异质结可以利用各组份二维材料的优异物理性质，实现按需设计制备新型的功能器件。通过构建二维半导体材料MoS₂与二维铁电材料In₂Se₃的异质结，研究了铁电极化对异质结的能带结构、电荷转移、压电系数及光电响应的影响。结果发现：当极化方向沿着从MoS₂指向In₂Se₃方向时，异质结能量更低、结构更稳定、电荷转移更多、能带带隙也更小；相比于面内应变对异质结带隙产生的微弱影响，利用极化方向的翻转可有效地调控异质结的带隙，实现从Ⅰ型能带对齐到Ⅱ型能带对齐；针对最稳定的异质结结构，发现压电系数e₃₁相比于单层In₂Se₃提升了24倍。通过实验采用干法转移制备出MoS₂/In₂Se₃异质结，利用拉曼光谱与光致发光光谱对其光电特性进行表征，发现异质结区保留着各自组份材料的拉曼特征峰与激子峰信号，相比于单独的In₂Se₃，异质结对In₂Se₃激子峰具有荧光增强效应。

Abstract:

Two-dimensional （2D） material heterojunctions can utilize the excellent physical properties of each component to achieve the on-demand design and preparation of new functional devices. In this paper， the influence of ferroelectric polarization on the electronic band structure， charge transfer and piezoelectric coefficient of the heterostructure is theoretically studied by constructing the heterostructure of 2D semiconductor material MoS₂ and 2D ferroelectric material In₂Se₃. Research has found that when the polarization is along the direction from MoS₂ to In₂Se₃， the configuration is more stable， resulting in more charge transfer and smaller band gap. Compared to the effect of in-plane strain on the band gap of heterojunction， the reversal of polarization direction can effectively regulate the band gap of heterojunctions， achieving band alignment from type I to type II. For the stable MoS₂/In₂Se₃ heterojunction， we found that the piezoelectric coefficient of e₃₁ is 24 times higher than that of single-layer In₂Se₃. Finally， we experimentally prepared the MoS₂/In₂Se₃ heterojunction through dry transfer technic， and characterized it using Raman spectroscopy and photoluminescence spectroscopy. It was found that the heterojunction region retained the Raman spectra and exciton signals of its respective components， and compared to In₂Se₃ few layer， the heterostructure had a fluorescence enhancement effect on the In₂Se₃ exciton peak.