Large Memory Window of van der Waals Heterostructure Devices Based on MOCVD‐Grown 2D Layered Ge₄Se₉

Abstract

Van der Waals (vdW) heterostructures have drawn much interest over the last decade owing to their absence of dangling bonds and their intriguing low‐dimensional properties. The emergence of 2D materials has enabled the achievement of significant progress in both the discovery of physical phenomena and the realization of superior devices. In this work, the group IV metal chalcogenide 2D‐layered Ge4Se9 is introduced as a new selection of insulating vdW material. 2D‐layered Ge4Se9 is synthesized with a rectangular shape using the metalcorganic chemical vapor deposition system using a liquid germanium precursor at 240 °C. By stacking the Ge4Se9 and MoS2, vdW heterostructure devices are fabricated with a giant memory window of 129 V by sweeping back gate range of ±80 V. The gate‐independent decay time reveals that the large hysteresis is induced by the interfacial charge transfer, which originates from the low band offset. Moreover, repeatable conductance changes are observed over the 2250 pulses with low non‐linearity values of 0.26 and 0.95 for potentiation and depression curves, respectively. The energy consumption of the MoS2/Ge4Se9 device is about 15 fJ for operating energy and the learning accuracy of image classification reaches 88.3%, which further proves the great potential of artificial synapses.

Recent Advances in the Preparation and Application of Two-Dimensional Nanomaterials

“…By utilizing thermal decomposition reactions in VPE on a substrate, MOCVD can produce thin-layer single-crystal materials, including various III-V, II-VI compound semiconductors and their multilayer solid solutions [65]. Noh [66] utilized a metalorganic CVD system to synthesize rectangular-shaped 2D-layered Ge 4 Se 9 using a liquid germanium precursor at 240 • C. Their MOCVD reactor is equipped with a two-zone heating system, allowing for the precise control of precursor decomposition in the first heating zone (T 1 = 480 • C) and separate crystal synthesis in the second heating zone (T 2 from 240 to 400 • C). In their experiment, Ge(dmamp) 2 and dimethyl selenide (CH 3 ) 2 Se were employed as the precursors for Ge and Se, respectively, while muscovite mica served as the substrate.…”

Quantum tailoring for polarization-discriminating Bi2S3 nanowire photodetectors and their multiplexing optical communication and imaging applications

“…), and 2D vdWMs ( e.g. , black phosphorus, 13 MoS 2 , 14,15 WSe 2 , 15 Bi 2 O 2 Se, 16 ReSe 2 , 17 CrTe 2 , 18 Ge 4 Se 9 , 19 ZnIn 2 S 4 , 20 AgInP 2 S 6 , 21 etc. ).…”

Memory Window Ratio Enhancement of p-Type WSe2 Memtransistors Using Dielectric GeSe2 Nanosheets with Asymmetric Interfaces for Neuromorphic Computing

“…26 Interface defects in Ge 4 Se 9 play a key role as a charge trap layer in inducing hysteresis behavior. 27 However, 2D materials include two surfaces, i.e., one side can be functionalized for charge trapping and the other can suppress carrier scattering from the channel−dielectric interface, thereby obtaining high-field-effect mobility. Therefore, Janus 2D WBGSs, obtained through asymmetric functionalization, will be a tailor-made architecture for the development of high-performance neuromorphic computing 2D circuits.…”

“…Surface vacancies in Ruddlesden–Popper perovskite (2D-RPP) serve as effective electron trapping sites in the dielectric-free MoS 2 /2D-RPP heterojunction memtransistor . Interface defects in Ge 4 Se 9 play a key role as a charge trap layer in inducing hysteresis behavior . However, 2D materials include two surfaces, i.e., one side can be functionalized for charge trapping and the other can suppress carrier scattering from the channel–dielectric interface, thereby obtaining high-field-effect mobility.…”