Cross-field optoelectronic modulation via inter-coupled ferroelectricity in 2D In2Se3

Abstract

The ability to couple the in-plane (IP) and out-of-plane (OOP) dipole polarizations in ferroelectric In2Se3 makes it a promising material for multimodal memory and optoelectronic applications. Herein, we experimentally demonstrate the cross-field optoelectronic modulation in In2Se3 based field-effect devices. Surface potential measurements of In2Se3 based devices directly reveal the bidirectional dipole locking following high gate voltage pulses. The experimental evidence of hysteretic change in the IP electrical field facilitating a nonvolatile memory switch, was further explored by performing photocurrent measurements. Fabricated photodetectors presented multilevel photocurrent characteristics showing promise for nonvolatile memory and electro-optical applications.

Indium Selenide (In2Se3) – An Emerging Van‐der‐Waals Material for Photodetection and Non‐Volatile Memory Applications

“…[114] In addition, two peaks close to 180 � 3 cm À 1 and 195 � 3 cm À 1 are attributed to the A 1 (LO) and A 1 (TO) modes, respectively, are assigned to intra-layer vibrations. [66,114] This LO-TO splitting confirmed the lack of inversion symmetry in the R3m asymmetric structure, consistent with the STEM and SHG study. [59] In particular, a small but distinct Raman feature at 266 cm À 1 , which could be regarded as the determinant evidence for the crystal structure of ferroelectric α-In 2 Se 3 .…”

“…This identification peak corresponding to the A 1 [LO (longitudinal optical) +TO (transverse optical)] mode is the sum of the two E‐modes (19 and 84 cm −1 ) and attributed to shear vibrations of one layer against others along the c‐axis [114] . In addition, two peaks close to 180±3 cm −1 and 195±3 cm −1 are attributed to the A 1 (LO) and A 1 (TO) modes, respectively, are assigned to intra‐layer vibrations [66,114] . This LO‐TO splitting confirmed the lack of inversion symmetry in the R3m asymmetric structure, consistent with the STEM and SHG study [59] .…”

“…Mechanical exfoliation (also referred to as “Scotch‐tape” exfoliation) from the bulk crystal using adhesive tape is the most well‐known route to produce high quality atomically thin 2D flakes [65–67] . The adhesive force between the tape and top layers of In 2 Se 3 is strong enough to overcome the weak vdW interaction between two adjacent layers in a bulk crystal, which leads to the layer‐by‐layer isolation.…”

“…Dutta et al. demonstrated that the change in non‐volatile memory states by reversing the polarization direction could facilitate multilevel photocurrent modulations (Figure 18(e)–(f)) [66] . They showed the photocurrent could be changed from 19.38±0.32 nA (for unpoled device) to 10.84±0.31 nA (for upward polarization) and 28.15±0.62 nA (for downward polarization), which can be utilized to fabricate multifunctional memory cells.…”

“…Mechanical exfoliation (also referred to as "Scotch-tape" exfoliation) from the bulk crystal using adhesive tape is the most well-known route to produce high quality atomically thin 2D flakes. [65][66][67] The adhesive force between the tape and top layers of In 2 Se 3 is strong enough to overcome the weak vdW interaction between two adjacent layers in a bulk crystal, which leads to the layer-by-layer isolation. In contrast, the IP covalent bonds within each layer remain intact and preserve their crystallinity that is most appealing for fundamental research on intrinsic properties and for achieving superior device performance.…”