Electrical Properties in Ta2NiSe5 Film and van der Waals Heterojunction

Masaya Fukai,Yoshio Hashimoto,Noriyuki Urakami

doi:10.3390/coatings11121485

Abstract

Ternary Ta2NiSe5 is a novel electronic material having the property of an excitonic insulator at room temperature. The electrical properties of Ta2NiSe5 have not been elucidated in detail. We discuss the electronic properties in Ta2NiSe5 films and the formation of heterojunctions. Hall effect measurements showed p-type conductivity. The activation energies estimated from the temperature dependence of the carrier concentration were seen to be 0.17 eV and 0.12 eV, at approximately 300 and 400 K, respectively. It was observed that carrier generation behavior changes at the critical temperature of the excitonic insulator state (328 K). The temperature dependence of the Hall mobility below the critical temperature nearly follows the bell-shaped curves for conventional semiconductor materials. A MoS2/Ta2NiSe5 van der Waals heterojunction was fabricated using the transfer method. Rectification characteristics, which depend on the gate bias voltage, were obtained. The barrier height at the MoS2/Ta2NiSe5 heterointerface and the on/off ratio could be modulated by applying a gate bias voltage, suggesting that the carrier transport was exhibited in band-to-band flow. Our demonstration suggests that the knowledge of Ta2NiSe5 increased as an electronic material, and diode performance was successfully achieved for the electronic device applications.

Highlights

We focused on Ta2 NiSe5, for which the detailed electrical properties have not been elucidated, and there have been no demonstrations of heterojunctions with other materials
Ta2NiSe5 crystals were fabricated via the chemical vapor transport (CVT) method in sealed quartz tubes
The morphology and elemental analysis of the Ta2 NiSe5 crystals were observed usingFigure scanning electron microscopy equipped with spectroscopy

Summary

Introduction

Optoelectronic devices of layered materials offer several novel applications. In addition to electronic devices (field effect transistors [1] and memory devices [2]) and optical devices (light emitting devices [3] and photodetectors [4]), they have been considered as metamaterials [5,6], which can be engineered to manipulate electromagnetic waves and to produce unconventional optical properties [7,8,9]. Transition metal chalcogenides have received much attention as novel optoelectronic materials. The physical properties of these materials are changed by the selection of constituent elements, such as semiconducting (MoW) (SSe) , superconducting FeSe2 or NbSe2 , and ferromagnetic (CrFe)GeS3 [10,11,12,13]

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Results

Conclusion