Program 2nd Workshop „2D Materials for Future Electronics“

Jinxin Liu (TU Dresden)

2D conjugated metal-organic frameworks towards monolithic 3D integration

Monolithic three-dimensional (3D) integration based on vertically stacked two-dimensional (2D) materials offers a compelling alternative to conventional planar integrated circuits, enabling higher integration density while reducing interconnect latency and power consumption and, ultimately, expanding functionality beyond Moore’s scaling. A central prerequisite for industrial translation is the controllable, wafer-scale synthesis of high-quality 2D active layers under low thermal budgets (<400 °C). However, widely used inorganic 2D materials, such as MoS₂, graphene, and h-BN, are governed by strong covalent bonding; achieving high crystallinity typically requires high growth temperatures to overcome substantial reaction barriers and to enable reversible bond breaking/forming, thereby challenging to make wafer-scale high-quality films at low temperatures.

In contrast, 2D conjugated metal–organic frameworks (2D c-MOFs) are assembled from π-conjugated organic linkers and metal nodes through coordination chemistry, which is thermodynamically favorable and generally characterized by low kinetic barriers. As a result, 2D c-MOFs can be formed at intrinsically low temperatures (often <200 °C) while offering rich and tunable charge-transport behaviors enabled by in-plane π–d conjugation. These features make them promising building blocks for monolithic, multifunctional integration. In this talk, I will present our efforts to establish chemical vapor deposition (CVD) as a scalable route to large-area, uniform 2D c-MOF thin films with device-relevant crystallinity and ultrasmooth surfaces. I will further discuss how such vapor-grown films can be directly integrated into electronic platforms, highlighting high-performance device demonstrations including photodetectors, and outlining key structure–property relationships that guide the design of 2D-c-MOF-based electronic units for low-temperature 3D integration. [/av_toggle] [av_toggle title='12:05 - 12:35 - Susanne Hoffmann-Eifert (Research Center Jülich) - Volatile ECM Cells from MOCVD-grown h-BN Layers for Neuromorphic Applications ' title_open='' tags='' title_pos='' slide_speed='' custom_id='' aria_collapsed='' aria_expanded='' av_uid='av-mkxz4xc6-1-1' sc_version='1.0']  Susanne Hoffmann-Eifert (Research Center Jülich)

Volatile ECM Cells from MOCVD-grown h-BN Layers for Neuromorphic Applications

Volatile-switching electrochemical metallization memory (v-ECM) cells show interesting properties for selector and neuromorphic computing applications, such as for example spiking neural networks (SNN) and leaky-integrated-and-fire (LIF) circuits. For the computation by dynamics and time new technologies for devices with high dynamics are required [1]. Among the various threshold-type devices, v-ECM also known as diffusive memristor is very promising [2]. The device switches from the high-resistance to the low-resistance state when the voltage rises above the threshold voltage and automatically restores the high-resistance state after a relaxation time when the voltage falls below the holding voltage. The advantage of v-ECMs compared to insulator-to-metal-based threshold switches is their extremely low leakage current and the low threshold voltages, while a drawback is the higher switching variability. In previous studies, we have investigated the SET kinetics and relaxation dynamics of v-ECM threshold switches based on Ag/HfO₂/Pt crossbar devices and demonstrated a correlation between the relaxation time and the operating parameters with reference to the SET kinetics [3,4].

This work focuses on the use of h-BN layers as the switching matrix in v-ECM devices. The h-BN layers were grown on sapphire substrates by metal organic chemical vapor deposition (MOCVD) in an AIXTRON CCSÒ reactor using triethylboron, ammonia and hydrogen as precursors. The influence of the growth conditions on the thin films’ structure and morphology was carefully analysed. Crossbar devices with Ag/h-BN/Pt structure were fabricated from transferred h-BN layers with thickness as low as 3 nm. The electrical properties and the resistive switching performance of the fabricated devices are discussed in the light of the thin films’ morphology. Finally, consequences for the desired material properties for reliable and reproducible switching devices are discussed.

References

[1] M. Dutta et al., Adv. Electron. Mater. 2024, 10, 2400221.

[2] Z. Wang, et al., Nature Mater 2017, 16, 101–108.

[3] S. Chekol et al., Adv. Funct. Mater. 2022, 32, 2111242

[4] S. Chekol et al., Adv. Electron. Mater. 2022, 8, 2200549.