Metal to Insulator Quantum-Phase Transition in Few-Layered ReS₂

Abstract

In ReS 2 a layer-independent direct band-gap of 1.5 eV implies a potential for its use in optoelectronic applications. ReS 2 crystallizes in the 1T'-structure which leads to anisotropic physical properties and whose concomitant electronic structure might host a non-trivial topology. Here, we report an overall evaluation of the anisotropic Raman response and the transport properties of fewlayered ReS 2 field-effect transistors. We find that ReS 2 exfoliated on SiO 2 behaves as an n-type semiconductor with an intrinsic carrier mobility surpassing µ i ~30 cm 2 /Vs at T = 300 K which increases up to ~350 cm 2 /vs at 2 K. Semiconducting behavior is observed at low electron densities n, but at high values of n the resistivity decreases by a factor > 7 upon cooling to 2 K and displays a metallic T 2 -dependence. This indicates that the band structure of 1T'-ReS 2 is quite susceptible to an electric field applied perpendicularly to the layers. The electric-field induced metallic state observed in transition metal dichalcogenides was recently claimed to result from a percolation type of transition. Instead, through a scaling analysis of the conductivity as a function of T and n, we find that the metallic state of ReS 2 results from a second-order metal to insulator transition driven by electronic correlations. This gate-induced metallic state offers an alternative to phase engineering for producing ohmic contacts and metallic interconnects in devices based on transition metal dichalcogenides.

Electroluminescence from indirect band gap semiconductor ReS 2

“…To this end we have used the SiO 2 /Si (back) gate present in our devices to assess their quality prior to the IL gate measurements, and to compare the performance of the devices operated with the two different gates. Since ReS 2 is generally found to be n-doped [22,23,25,26] and hole transport cannot be induced using a Si/SiO 2 gate, for this comparison we focus on electron transport. Figure 1(d) shows the same comparison for the conductivity extracted from four terminal measurements, to eliminate the effect of the contact resistance and to account for the device geometry.…”

Advent of 2D Rhenium Disulfide (ReS2): Fundamentals to Applications

“…Therefore ReS2 exhibits semiconductor-to-metallic behaviour at high electron densities and low temperatures. [69] This is because at high densities of electrons resistivity decreases significantly. The metallic state of ReS2 is a result of second-order metal-to-insulator transition driven by electronic correlation.…”

“…[18,26,27,64,69,[87][88][89][90][91][92][93] For example, Shim et al [91] , Corbet et al [87,92] and Liu et al [27] reported ReS2-based TFTs with high on/off current ratio of 10 7 , 10 4 and 10 5 , respectively, and Zhang et al [89] and Liu et al [27] demonstrated ReS2-based photodetectors with a photoresponsivity of 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 -1 , respectively. Prototypes of ReS2 based FET, photodetector and digital inverter are shown in Figure 10.…”

Electronic and Optoelectronic Applications Based on ReS2

“…The resistivity of ReS 2 and the inherent carrier mobility are both dependent on temperature and electron density . Low temperature measurements allow ReS 2 to exhibit semiconductor to metallic behavior at high electron densities, which indicates that the carrier mobility is inversely proportional to temperature. The reason is that resistivity reduces considerably under the condition of high electron densities.…”