In this thesis we focus on investigation of different aspects of a conceptually unique non-volatile charge configuration memory (CCM) device based on resistive switching between different electronic states in 1T-TaS2 material. We find that CCM devices feature energy-efficient (2.2 fJ/bit) and ultrafast switching (2 ps), very good endurance and a straightforward design. They can operate at cryogenic temperatures, which makes them ideal for integration into emerging cryo-computing and other high-performance computing systems such as superconducting quantum computers, which are currently hindered by the absence of a suitable memory device. We explore energy efficiency scaling of the CCM device as a function of device size and data write time τW, as well as other parameters that have bearing on efficient device performance, such as potential interfacial layers in the electrical contact structure and heating effects during operation.
We also microscopically examine the intricate domain wall network of the metastable H state in 1T-TaS2 material and observe its dynamics under applied current using a scanning tunnelling microscope (STM). We observe non-thermal formation of a topologically protected entangled network of dislocations interconnected by domain walls that leads to robustness of the metastable state to external perturbations, and provides non-volatile behaviour to the CCM device. By detailed modelling and analysis of the annihilation of the domain wall network we gain insight into the underlying physics of the metastable state and by extension the CCM device.
We investigate a possible implementation of the non-volatile CCM device in a cryo computing environment by combining it in parallel with a superconducting amplifying nanocryotron (nTron) element, which can be driven by extremely small single-flux-quantum (SFQ) logic, while offering an excellent match to the CCM device in terms of output impedance, output voltage and operational speed. We examine this new hybrid ’parallelotron’ (pTron) device, comprising the CCM and nTron in parallel connection, through numerical calculations of time-dynamics and voltage-current characteristics, as well as experimentally, where preliminary results confirm the envisioned memory operation. The immediate challenges for advancing this technology lie in the co-fabrication of devices that combine 1T-TaS2 and superconducting SFQ-based technology. The inherent high energy efficiency and ultrahigh speed makes the pTron device an ideal memory for use in cryo computing and quantum computing peripheral devices.
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