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Charge transport in MBE-grown 2H-MoTe2 bilayers with enhanced stability provided by an AlOx capping layer.
Nanoscale ( IF 5.8 ) Pub Date : 2020-07-08 , DOI: 10.1039/d0nr03148h Zuzanna Ogorzałek 1 , Bartłomiej Seredyński 1 , Sławomir Kret 2 , Adam Kwiatkowski 1 , Krzysztof P Korona 1 , Magdalena Grzeszczyk 1 , Janusz Mierzejewski 1 , Dariusz Wasik 1 , Wojciech Pacuski 1 , Janusz Sadowski 3 , Marta Gryglas-Borysiewicz 1
Nanoscale ( IF 5.8 ) Pub Date : 2020-07-08 , DOI: 10.1039/d0nr03148h Zuzanna Ogorzałek 1 , Bartłomiej Seredyński 1 , Sławomir Kret 2 , Adam Kwiatkowski 1 , Krzysztof P Korona 1 , Magdalena Grzeszczyk 1 , Janusz Mierzejewski 1 , Dariusz Wasik 1 , Wojciech Pacuski 1 , Janusz Sadowski 3 , Marta Gryglas-Borysiewicz 1
Affiliation
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Thin layers of transition metal dichalcogenides have been intensively studied over the last few years due to their novel physical phenomena and potential applications. One of the biggest problems in laboratory handling and moving on to application-ready devices lies in the high sensitivity of their physicochemical properties to ambient conditions. We demonstrate that novel, in situ capping with an ultra-thin, aluminum film efficiently protects thin MoTe2 layers stabilizing their electronic transport properties after exposure to ambient conditions. The experiments have been performed on bilayers of 2H-MoTe2 grown by molecular beam epitaxy on large area GaAs(111)B substrates. The crystal structure, surface morphology and thickness of the deposited MoTe2 layers have been precisely controlled in situ with a reflection high energy electron diffraction system. As evidenced by high resolution transmission electron microscopy, MoTe2 films exhibit perfect arrangement in the 2H phase and the epitaxial relation to the GaAs(111)B substrates. After the growth, the samples were in situ capped with a thin (3 nm) film of aluminum, which oxidizes after exposure to ambient conditions. This oxide serves as a protective layer to the underlying MoTe2. Resistivity measurements of the MoTe2 layers with and without the cap, exposed to low vacuum, nitrogen and air, revealed a huge difference in their stability. The significant rise of resistance is observed for the unprotected sample while the resistance of the protected one is constant. Wide range temperature resistivity studies showed that charge transport in MoTe2 is realized by hopping with an anomalous hopping exponent of x ≃ 0.66, reported also previously for ultra-thin, metallic layers.
中文翻译：
由AlOx覆盖层提供的MBE生长2H-MoTe2双层中的电荷传输具有增强的稳定性。
在过去的几年中，过渡金属二卤化硅的薄层由于其新颖的物理现象和潜在的应用而得到了深入的研究。实验室处理和转向应用就绪设备的最大问题之一是其理化性质对环境条件的高度敏感性。我们证明了新型，超薄铝膜原位覆盖技术有效地保护了MoTe 2薄层，使其在暴露于环境条件后稳定了其电子传输性能。实验是在分子束外延在大面积GaAs（111）B衬底上生长的2H-MoTe 2双层上进行的。沉积的MoTe的晶体结构，表面形态和厚度利用反射高能电子衍射系统精确地控制了2个层。如高分辨率透射电子显微镜所证明的，MoTe 2薄膜在2H相中显示出完美的排列，并且与GaAs（111）B衬底具有外延关系。生长后，将样品原位盖上铝薄（3 nm）薄膜，铝薄膜在暴露于环境条件后会氧化。该氧化物用作下层MoTe 2的保护层。MoTe 2的电阻率测量暴露于低真空，氮气和空气下的带盖和不带盖的涂层显示出其稳定性的巨大差异。对于未保护的样品，观察到电阻显着上升，而被保护的样品的电阻是恒定的。宽温度范围内的电阻率的研究表明在该微尘电荷传输2是通过用的异常跳频指数跳频实现X ≃0.66，还预先为超薄，金属层的报道。
更新日期：2020-08-14
中文翻译：
由AlOx覆盖层提供的MBE生长2H-MoTe2双层中的电荷传输具有增强的稳定性。
在过去的几年中，过渡金属二卤化硅的薄层由于其新颖的物理现象和潜在的应用而得到了深入的研究。实验室处理和转向应用就绪设备的最大问题之一是其理化性质对环境条件的高度敏感性。我们证明了新型，超薄铝膜原位覆盖技术有效地保护了MoTe 2薄层，使其在暴露于环境条件后稳定了其电子传输性能。实验是在分子束外延在大面积GaAs（111）B衬底上生长的2H-MoTe 2双层上进行的。沉积的MoTe的晶体结构，表面形态和厚度利用反射高能电子衍射系统精确地控制了2个层。如高分辨率透射电子显微镜所证明的，MoTe 2薄膜在2H相中显示出完美的排列，并且与GaAs（111）B衬底具有外延关系。生长后，将样品原位盖上铝薄（3 nm）薄膜，铝薄膜在暴露于环境条件后会氧化。该氧化物用作下层MoTe 2的保护层。MoTe 2的电阻率测量暴露于低真空，氮气和空气下的带盖和不带盖的涂层显示出其稳定性的巨大差异。对于未保护的样品，观察到电阻显着上升，而被保护的样品的电阻是恒定的。宽温度范围内的电阻率的研究表明在该微尘电荷传输2是通过用的异常跳频指数跳频实现X ≃0.66，还预先为超薄，金属层的报道。
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