Optoelectronic Synapse Behaviors of HfS2 Grown via Molten Salt Flux Method

• Published in: Electronic materials letters Vol. 20; no. 5; pp. 559 - 570
• Main Authors: Kwon, Mi Ji, Binh, Nguyen Vu, Cho, Su-yeon, Shim, Soo Bin, Ryu, So Hyun, Jung, Yong Jae, Nam, Woo Hyun, Cho, Jung Young, Park, Jun Hong
• Format: Journal Article
• Language: English
• Published: Seoul The Korean Institute of Metals and Materials 01.09.2024; Springer Nature B.V; 대한금속·재료학회
• Subjects: Characterization and Evaluation of Materials; Chemical properties; Chemical synthesis; Chemistry and Materials Science; Condensed Matter Physics; Field effect transistors; Hafnium compounds; Magnetics and Photonics; Materials Science; Modulation; Molten salts; Nanotechnology; Nanotechnology and Microengineering; Optical and Electronic Materials; Optoelectronics; Original Article - Electronics; Photoelectrons; Raman spectroscopy; Semiconductor devices; Spectrum analysis; Thin bodies; Transition metal compounds; Two dimensional bodies; Two dimensional materials; X ray photoelectron spectroscopy; 전자/정보통신공학; Transistor; Molten salt flux method; HfS; Transition metal dichalcogenide; Optoelectronic synapse device
• ISSN: 1738-8090; 2093-6788
• DOI: 10.1007/s13391-024-00494-z

Layered two-dimensional materials are promising candidates for next-generation semiconductor platforms owing to their atomically thin bodies, and it is crucial to develop a method for their large-scale synthesis for integrating these materials into the fabrication process. Here, we report the synthesis of a centimeter-scale HfS 2 ingot using the molten salt flux method (MSFM). The structure, crystallinity, and uniformity of the synthesized HfS 2 sample were verified using X-ray diffraction and Raman spectroscopy. The chemical properties were investigated using X-ray photoelectron spectroscopy. A HfS 2 synaptic field effect transistor (FET) was fabricated to confirm its electrical uniformity and semiconducting nature, with an average mobility of 10.6 cm 2 V -1 s -1 . The synaptic plasticity of the HfS 2 synaptic FET was investigated by applying light pulses (405 nm) in different modulation configurations. Paired-pulse facilitation was achieved by applying a continuous light pulse with a negative gate bias voltage. The modulation of synaptic weight was demonstrated under different stimulation conditions, which emulates the human brain. Furthermore, the linearity of the HfS 2 synaptic device was optimized based on the frequency of the pulses to enhance learning accuracy. The approach reported here encourages the large-scaled production of transition metal dichalcogenides (TMDs) for use in artificial synaptic transistors. Graphical Abstract