Epitaxial Single‐Layer MoS2 on GaN with Enhanced Valley Helicity,Advanced Materials

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Epitaxial Single‐Layer MoS2 on GaN with Enhanced Valley Helicity
Advanced Materials ( IF 27.4 ) Pub Date : 2017-12-19 , DOI: 10.1002/adma.201703888
Yi Wan ₁ , Jun Xiao ₂ , Jingzhen Li ₁ , Xin Fang ₁ , Kun Zhang ₁ , Lei Fu ₁ , Pan Li ₁ , Zhigang Song ₁ , Hui Zhang ₁ , Yilun Wang ₁ , Mervin Zhao ₂ , Jing Lu _{1,

3} , Ning Tang _{1,

3} , Guangzhao Ran ₁ , Xiang Zhang _{2,

4} , Yu Ye _{1,

3} , Lun Dai _{1,

3}

Affiliation

Engineering the substrate of 2D transition metal dichalcogenides can couple the quasiparticle interaction between the 2D material and substrate, providing an additional route to realize conceptual quantum phenomena and novel device functionalities, such as realization of a 12‐time increased valley spitting in single‐layer WSe₂ through the interfacial magnetic exchange field from a ferromagnetic EuS substrate, and band‐to‐band tunnel field‐effect transistors with a subthreshold swing below 60 mV dec⁻¹ at room temperature based on bilayer n‐MoS₂ and heavily doped p‐germanium, etc. Here, it is demonstrated that epitaxially grown single‐layer MoS₂ on a lattice‐matched GaN substrate, possessing a type‐I band alignment, exhibits strong substrate‐induced interactions. The phonons in GaN quickly dissipate the energy of photogenerated carriers through electron–phonon interaction, resulting in a short exciton lifetime in the MoS₂/GaN heterostructure. This interaction enables an enhanced valley helicity at room temperature (0.33 ± 0.05) observed in both steady‐state and time‐resolved circularly polarized photoluminescence measurements. The findings highlight the importance of substrate engineering for modulating the intrinsic valley carriers in ultrathin 2D materials and potentially open new paths for valleytronics and valley‐optoelectronic device applications.

中文翻译：

具有增强的谷底螺旋性的GaN外延单层MoS2

对2D过渡金属二硫化氢的衬底进行工程设计可以耦合2D材料和衬底之间的准粒子相互作用，从而提供了另一条途径来实现概念量子现象和新颖的器件功能，例如在单层WSe中实现12倍增加的谷值溅射。₂通过铁磁性EuS衬底的界面磁场交换场以及室温下基于双层n- MoS ₂和重掺杂p-锗的亚阈值摆幅低于60 mV dec ^-1的带间隧道场效应晶体管等等。在这里，证明了外延生长的单层MoS ₂在具有I型能带对准的晶格匹配GaN衬底上，显示出很强的衬底诱导的相互作用。GaN中的声子通过电子-声子相互作用迅速耗散了光生载流子的能量，从而导致MoS ₂ / GaN异质结构中的激子寿命短。通过这种相互作用，可以在稳态和时间分辨圆偏振光致发光测量中观察到室温下的谷底螺旋度增强（0.33±0.05）。这些发现凸显了基板工程对于调制超薄2D材料中固有的谷底载流子的重要性，并为谷底电子学和谷底光电子器件的应用打开了新的途径。

更新日期：2017-12-19

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