Room-temperature out-of-plane and in-plane ferroelectricity of two-dimensional β-InSe nanoflakes

Abstract

Two-dimensional (2D) layered semiconductors have shown great application potential in next generation nanoelectronic devices. The ferroelectric and piezoelectric properties of 2D semiconductors are also highly desirable in many applications, such as ferroelectric nonvolatile memory and switch. In the present work, we experimentally demonstrate the simultaneous out-of-plane and in-plane ferroelectricity of β-indium selenide (β-InSe) nanoflakes at room temperature. The polarization switching in the as-prepared β-InSe with the P63/mmc symmetry is studied by piezoresponse force microscopy. Out-of-plane polarization hysteresis loops are observed in a 7-nm-thick sample, and the in-plane and out-of-plane ferroelectric switching under the forward and reverse direct current bias are obtained in a 10-nm-thick sample at room temperature. These results indicate that β-InSe is a promising intrinsic 2D van der Waals ferroelectric material. Our work has connected the 2D materials with ferroelectric materials and inspired their applications in electronic devices.

Two-Dimensional CIPS-InSe van der Waal Heterostructure Ferroelectric Field Effect Transistor for Nonvolatile Memory Applications

“…InSe displays high mobility (≈10 3 cm 2 /V) because of its marginal effective mass ( m e * = 0.14 m o ) and room-temperature stability with a honeycomb lattice in a Se–In–In–Se covalent configuration . Hu et al , experimentally demonstrated the coexistence of in-plane and out-of-plane ferroelectricity in 7 nm thick InSe flakes and the effect of its polarization on the drain current characteristics. In this study, we utilized the ferroelectric and semiconducting properties of InSe layers used as the channel material for FeFETs integrated with CIPS ferroelectric dielectric.…”

Two-Dimensional van der Waals Ferroelectrics: Scientific and Technological Opportunities

“…For example, a vertical polarization over 2 pC/m will be reversed upon interlayer translation of a BN bilayer from AB stacking to BA stacking, as shown in Figure a. Such unique FEs exist in many van der Waals bilayers, multilayers, and even bulk structures, including BN, MoS 2 , and InSe (see Figure b), which were later experimentally confirmed in WTe 2 ,, (Figure c), as well as in BN , and InSe bilayer/multilayers. For example, Fei et al measured the vertical polarization of WTe 2 bilayers using the device shown in Figure c, and the result was consistent with theoretical predictions .…”

“…In recent years, some researchers have focused on FMs and FEs in two-dimensional (2D) van der Waals materials with atomic thicknesses. The theoretical designs of FEs in 2D materials date back to 2013, and some have since been experimentally verified, such as IV–VI group compounds − (SnTe, SnSe, SnS , ), In 2 Se 3 , − van der Waals bilayer/multilayer, − distorted 1T MoS 2 , , and Bi 2 O 2 Se. , The discovery of ferroelectricity in CuInP 2 S 6 , and hybrid perovskite bis­(benzylammonium) lead tetrachloride (BA 2 PbCl 4 ) thin layers has also been reported, without related technological predictions. The Curie temperatures of all of these 2D FE systems are above room temperature for practical applications, which remains a challenge for 2D FMs. , Such stability can be attributed to the much larger switching barriers of electric dipoles compared with spins, in general, which may ensure robustness, even in two dimensions.…”

Ultrasensitive Ferroelectric Semiconductor Phototransistors for Photon‐Level Detection

“…Considering the fundamental mechanism, we believe the phononema observed here may be generalized to other emerging ferroelectric semiconducting materials like β‐InSe and SnTe. [ 44,45 ]…”

“…Considering the fundamental mechanism, we believe the phononema observed here may be generalized to other emerging ferroelectric semiconducting materials like β-InSe and SnTe. [44,45] Figure 5a,b summarizes the performances of state-of-the-art photosensors, including Si-based commercial photodiode, commercial APD, commercial PMT, and photodetectors based on emerging two-dimensional (2D) materials reported (for detailed information, see Table S1, Supporting Information). The FSP has a higher R of 3.98 × 10 6 A/W, a lowest NEP of 7.9 × 10 -22 W − Hz 1/2 , and a highest D* of 6.34 × 10 17 Jones (Figure S27, Supporting Information).…”