InSe: a two-dimensional semiconductor with superior flexibility

Abstract

Two-dimensional Indium Selenide (InSe) has attracted extensive attention recently due to its recordhigh charge carrier mobility and photoresponsivity in the fields of electronics and optoelectronics. Nevertheless, the mechanical properties of this material in the ultra-thin regime have not been investigated yet. Here, we present our efforts to determine the Young's modulus of thin InSe (~1-2 layers to ~40 layers) flakes experimentally by using buckling-based methodology. We find that the Young's modulus has a value of 23.1 ± 5.2 GPa, one of the lowest values reported up to date for crystalline two-dimensional materials. This superior flexibility can be very attractive for different applications, such as strain engineering and flexible electronics.

Enhanced Optical Emission from 2D InSe Bent onto Si‐Pillars

“…The corresponding shift of the Raman peaks (Figure 3) supports a strain‐induced change of vibrational and electronic properties. [ 16–25,31 ] The bent layers are subject to a weak tensile and compressive strain in the outer and inner surfaces, respectively, which reduces the band gap energy (Figure S5, Supporting Information). Our calculated reduction of the band gap energy is in line with the measured energy shift (<5 meV) of the PL peak in the bent flakes.…”

“…[ 4,14,15 ] Thus, band edge excitons tend to couple preferentially to light polarized along the z‐direction (or c‐axis), rather than along the xy‐plane as for TMDCs. [ 4 ] Mechanical strain can modify these properties: [ 16–20 ] 2D vdW crystals can sustain high strain in reversible fashion due to their large mechanical flexibility [ 21–23 ] and, amongst them, InSe is one of the most flexible systems with a small Young's modulus (23.1 ± 5.2 GPa) [ 24 ] and a bandgap energy that is very sensitive to strain. [ 25 ] Thus, InSe represents a promising system to explore and exploit the effects of strain on electronic and optical properties.…”

The role of traps in the photocurrent generation mechanism in thin InSe photodetectors

“…Indium selenide (InSe), an n-type semiconductor which belongs to the IIIVIA family, has recently attracted large attention because of its extraordinary charge transport properties, superior mechanical flexibility and strong light-matter interaction. [23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41] Various groups have reported transistors based on thin InSe fabricated on different substrates (SiO 2 /Si, hexagonal Boron Nitride (h-BN), poly(methyl methacrylate) (PMMA)) with mobility values as large as 3700 cm 2 V À1 s À1 at room temperature and B13 000 cm 2 V À1 s À1 at 4 K. 23,[25][26][27][28] The bandgap of 1.3 eV in bulk that becomes larger than 3 eV for an InSe single-layer makes this material interesting for broadband photodetection from the nearinfrared to the near ultraviolet region of the electromagnetic spectrum. [30][31][32][33][34][35][36][37][38][39][40] Various photodetectors based on thin InSe flakes (as the active channel part), including metal-semiconductor-metal (M-S-M) geometry and graphene based van der Waals heterostructures, have been reported in the literature with responsivities going from 0.035 A W À1 to ultrahigh values of B10 7 A W À1 and detectivities up to B10 15 Jones [30][31][32][33]…”

Bioelectronics‐Related 2D Materials Beyond Graphene: Fundamentals, Properties, and Applications

“…Graphene has the largest Young's modulus and fracture strength among all natural materials. [32] 2D materials beyond graphene exhibit poorer mechanical properties, [33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49] but are still sufficiently strong for bioelectronic applications. Table 1 summarizes the mechanical properties of graphene and other 2D materials beyond graphene.…”