Ferroelectric-tuned van der Waals heterojunction with band alignment evolution

Yan Chen,Zhongming Wei,Xiaoting Wang,Peng Wang,Binmin Wu,Tie Lin,Hong Shen,Xiangjian Meng,Le Huang,Zhen Wang,Wei Jiang,Junhao Chu,Jianlu Wang,Xudong Wang,Weida Hu

doi:10.1038/s41467-021-24296-1

Abstract

Van der Waals integration with abundant two-dimensional materials provides a broad basis for assembling functional devices. In a specific van der Waals heterojunction, the band alignment engineering is crucial and feasible to realize high performance and multifunctionality. Here, we design a ferroelectric-tuned van der Waals heterojunction device structure by integrating a GeSe/MoS2 VHJ and poly (vinylidene fluoride-trifluoroethylene)-based ferroelectric polymer. An ultrahigh electric field derived from the ferroelectric polarization can effectively modulate the band alignment of the GeSe/MoS2 heterojunction. Band alignment transition of the heterojunction from type II to type I is demonstrated. The combination of anisotropic GeSe with MoS2 realizes a high-performance polarization-sensitive photodetector exhibiting low dark current of approximately 1.5 pA, quick response of 14 μs, and high detectivity of 4.7 × 1012 Jones. Dichroism ratios are also enhanced by ferroelectric polarization in a broad spectrum from visible to near-infrared. The ferroelectric-tuned GeSe/MoS2 van der Waals heterojunction has great potential for multifunctional detection applications in sophisticated light information sensing. More profoundly, the ferroelectric-tuned van der Waals heterojunction structure provides a valid band-engineering approach to creating versatile devices.

Highlights

Van der Waals integration with abundant two-dimensional materials provides a broad basis for assembling functional devices
A van der Waals (vdW) heterojunction (VHJ) is bond-free integration that is unaffected by the lattice mismatch or the processing condition of materials used
Ferroelectric field-effect transistors based on ferroelectrics and 2D materials have been demonstrated high performances and great potentials in electronics and optoelectronics[30,31,32]

Summary

Introduction

Van der Waals integration with abundant two-dimensional materials provides a broad basis for assembling functional devices. Under the modulation of P(VDF-TrFE) top gate, part of the trap states is localized by the polarization field, thereby narrowing the hysteresis window (Supplementary Fig. 3a). The P(VDF-TrFE) is supposed to modulate the band structure of GeSe. Detailed DFT calculations and experimental analysis are provided in Supplementary Figs.

Results

Conclusion