Characterization of metal contacts to Ta₂Ni₃Se₈ semiconducting nanowires

The 1D nanostructure of ternary transition metal chalcogenides M₂X₃Y₈ (M= Ta, Nb; X= Ni, Pd, Pt; Y= S, Se) have been found to exhibit remarkable electronic and optoelectronic properties. In this work, single crystals of centimeters long Ta₂Ni₃Se₈ bulk crystals were obtained by optimizing the growth temperature for solid-state growth. Nanowires were prepared from single crystals of Ta₂Ni₃Se₈ by mechanical exfoliation. Field-effect transistors in the back gate geometry had been successfully fabricated. Transport measurements at room temperature revealed that Ta₂Ni₃Se₈ nanowires exhibit n-type semiconducting behavior. Understanding the nature of the contacts is crucial for the study of the intrinsic properties of electronic devices. For charge carriers, barriers are often formed at the metal-semiconductor junction, which affects the charge carrier transport and significantly lowers the transistor performance. We studied the transport behavior of Ta₂Ni₃Se₈ nanowires contacted with different metals. Using a systematic temperature-dependent measurement, we found that electron transport through barriers dominated by thermionic emission. In addition, with a variable-length method, we demonstrate that resistance at each contact and the intrinsic resistivity can be accurately measured.