以凡得瓦限制輔助二碲化鎢之生長

Abstract

與其他Ⅵ族過渡金屬二硫屬化物不同，二碲化鎢是一種屬於斜方晶系 Td 相的半金屬。憑藉其非凡的性質，如 Weyl 半金屬態、巨磁阻和壓力誘發超導，二碲化鎢引起了人們的極大興趣。儘管具有豐富的獨特性質，快速氧化卻阻礙了功能性二碲化鎢元件向高性能方向發展。 在本研究中，我們通過固相反應實現了凡得瓦限制輔助二碲化鎢之合成。為了觀察壓力誘導的相變並降低二碲化鎢的氧化率，我們引入石墨烯作為自下而上的石墨烯/二碲化鎢異質結構的壓力源和鈍化層。與其他合成方法相比，選區電子衍射（SAED）和 X 射線光電子能譜（XPS）揭示了凡得瓦限制輔助合成的二碲化鎢具有單晶和較低的氧化率。 為了展示自下而上的石墨烯/二碲化鎢異質結構的元件性能，我們進行了析氫反應實驗。此外，我們還展示了透過硫屬原子取代二碲化鎢進行其他Ⅵ族鎢屬過渡金屬二硫屬化物的合成，為自下而上的橫向異質結構鋪路，並揭示了未來電子元件的可能性。

Unlike other group Ⅵ transition metal dichalcogenides (TMDCs), tungsten ditelluride (WTe2) is a semimetal with an orthorhombic Td phase. With its extraordinary properties, such as the Weyl semimetal state, giant magnetoresistance, and pressure-induced superconductivity, WTe2 has provoked tremendous interests. Although WTe2 owns fruitful distinctive characteristics, rapid oxidation hinders functional WTe2 devices toward high performance. In this study, we realize the van der Waals confinement-assisted synthesis of WTe2 by solid-state reaction. To observe the pressure-induced phase transition and decreases the oxidation ratio of WTe2, graphene is introduced as the pressure source and the passivation layer for the bottom-up graphene/WTe2 heterostructure. Compared to WTe2 synthesized by other methods, van der Waals confinement-assisted WTe2 with single crystalline and lower oxidation ratio has been revealed by the selected area electron diffraction (SAED) and X-ray photoelectron spectroscopy (XPS). Hydrogen evolution reaction experiment is conducted to demonstrate the device performance of bottom-up graphene/WTe2 heterostructure. Besides, other group Ⅵ W -based TMDCs synthesized by WTe2 through atomic substitution are demonstrated, paving the way for the bottom-up lateral heterostructure and unveiling the feasibility for the future electronics.