Multiterminal Transport Measurements of Multilayer InSe Encapsulated by hBN

Abstract

We investigate transport properties and scattering mechanisms of high-mobility InSe nanosheets, encapsulated by hBN, via four-terminal measurements. The measured conductivities increase as temperature (T) decreases, showing a metallic behavior at gate voltages above a threshold voltage, in contrast to the metal–insulator transition occurring at a high gate voltage observed in the two-terminal conductance of InSe. Phonon-limited and impurity-limited mobilities were separated for each carrier density (n) and T. Extracted impurity-limited mobility values are weakly dependent on n due to dominant short-range scatterers, while phonon-limited mobility values decrease as n increases due to second subband occupation and increased electron–phonon scattering.

High-Field Electron Transport and High Saturation Velocity in Multilayer Indium Selenide Transistors

“…Figure 2b shows the field-effect mobility, μ = dσ 4pt /dV BG (1/ C), of our InSe as a function of T, where C is the back gate capacitance per unit area, along with the previously reported μ values of other InSe devices for comparison. 15,16 D1 shows the highest μ, reaching 2600 cm 2 /(V s) at T = 290 K, superior to that of InSe sandwiched between hBN. 15,16 As T decreases, μ values gradually increase, following the standard T −1 dependence associated with acoustic phonon scattering.…”

“…32−34 The E a vs V BG dependencies in D1 and D2 align with those reported for InSe sandwiched between hBN. 16 The Arrhenius dependence begins to deviate at T ≈ 150 K, indicating the presence of an additional conduction mechanism in the insulating state (Figure 2c, left). At T < 150 K, the T-dependence of the insulating states of D1 (Figure 2c, right) and D2 (Figure S8, right) follows the 2D VRH model, σ 4pt = σ 2 T −0.8 exp(−(T 0 /T) 1/3 ), where T 0 is the characteristic temperature and σ 2 is a fitting parameter.…”

“…Indium selenide (InSe), with its moderate band gap (∼1.2 eV) and high electron mobility (>1000 cm 2 /(V s) at RT), − has allowed the development of various applications, such as photodetectors, , sensors, , memory devices, , and logic circuits. , Here, we report the υ sat of high-mobility vdW InSe, exceeding ∼2.0 × 10 7 cm/s at RT, which is superior to those of other vdW semiconductors. The InSe is on a hexagonal boron nitride (hBN) substrate and encapsulated by a thin, noncontinuous layer of In, which protects the InSe. , Notably, υ sat of our InSe exhibits a 50–60% improvement in υ sat when cooled to 80 K, showing its merit for low-temperature RF transistors.…”

Carrier and phonon transport in 2D InSe and its Janus structures

“…In 2021, Choi et al [105] investigated the electron scattering mechanisms in 30 nm InSe nanosheet at different temperatures. At low-temperature T < 100 K, the lattice vibration was gradually frozen, so impurity scattering becomes the dominant scattering mechanism in 2D InSe.…”

“…The second subband of the InSe was occupied as n increased. Besides the intra-band scattering, carriers suffer from inter-band scattering at high n, which decreases mobility [105].…”