• Gao, Zhangyuan
• Cheng, Matthew
• Dravid, Vinayak P.
• Reis, Roberto Dos
• Das, Paul Masih
• Tyner, Alexander
• Chen, Xinqi
• Shehzad, M. Arslan
• Goswami, Pallab
• Lebedev, Dmitry
• Hersam, Mark

Abstract

<jats:title>Abstract</jats:title><jats:p>Transition metal dichalcogenides (TMDs) are known for their layered structure and tunable functional properties. However, a unified understanding on other transition metal chalcogenides (i.e. M<jats:sub>2</jats:sub>X) is still lacking. Here, the relatively new class of copper-based chalcogenides Cu<jats:sub>2</jats:sub>X (X = Te, Se, S) is thoroughly reported. Cu<jats:sub>2</jats:sub>X are synthesized by an unusual vapor–liquid assisted growth on a Al<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub>/Cu/W stack. Liquid copper plays a significant role in synthesizing these layered systems, and sapphire assists with lateral growth and exfoliation. Similar to traditional TMDs, thickness dependent phonon signatures are observed, and high-resolution atomic images reveal the single phase Cu<jats:sub>2</jats:sub>Te that prefers to grow in lattice-matched layers. Charge transport measurements indicate a metallic nature at room temperature with a transition to a semiconducting nature at low temperatures accompanied by a phase transition, in agreement with band structure calculations. These findings establish a fundamental understanding and thrust Cu<jats:sub>2</jats:sub>Te as a flexible candidate for wide applications from photovoltaics and sensors to nanoelectronics.</jats:p>

Topics

• impedance spectroscopy
• phase
• layered
• phase transition
• copper
• chemical vapor deposition
• band structure