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Transport properties of SnTe nanowires in Josephson junction devices

Bošnjak, I. (2023) Transport properties of SnTe nanowires in Josephson junction devices.

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Embargo date:31 October 2026
Abstract:The rapid development of integrated circuits over the last decade led to high-performance systems which require immense cooling power. To reduce the need for cooling, dissipationless current transport is investigated. One material which could host dissipationless current is tin telluride (SnTe), a topological crystalline insulator (TCI), which enables edge and surface transport channels. However, SnTe is known to form tin vacancies, causing a problematic high bulk state conductance. The transport characteristics of a SnTe nanowire Josephson junction (JJ) device are analysed to find indications or lack of 2D and 1D transport channels on top of high bulk conductivity. The fabricated SnTe JJ devices are heavily underdamped with critical currents between 1.38 μA to 4.81 μA, retrapping currents between 0.11 μA to 0.26 μA, and normal resistances of about 36 Ω to 223 Ω for junction lengths between 260 nm to 410 nm. The highest IcRn product measured is 1.07 mV, and the lowest is 0.13 mV. Due to the heavily underdamped character of SnTe JJs, premature switching events distort the measurements, making fast measuring necessary. The current transport channels of SnTe nanowires can’t be depleted with an applied electric field, which confirms a high bulk conductivity in the fabricated SnTe JJ devices. Additionally, the Ic(T) relation of a device can be fitted with a purely diffusive model of a coherence length of 140 nm. In all devices, the critical current decays exponentially with an applied magnetic field. None of the devices show a purely homogeneous or one-dimensional current transport. Lastly, a SQUID is fabricated with SnTe nanowire JJs. The oscillation period matches up with the expected theoretical values, proving the functionality of an asymmetric SnTe SQUID. This makes it possible for the current phase relation to be extracted from the SnTe nanowires.
Item Type:Essay (Master)
Faculty:EEMCS: Electrical Engineering, Mathematics and Computer Science
Subject:33 physics, 51 materials science
Programme:Electrical Engineering MSc (60353)
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