VLSI Technology 2023
Conference paper

Quantum Dots Array on Ultra-Thin SOI Nanowires with Ferromagnetic Cobalt Barrier Gates for Enhanced Spin Qubit Control

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In this work we propose and demonstrate the integration of ferromagnetic nanosized cobalt barrier gates in quantum dots arrays on ultra-thin fully-depleted Silicon-On-Insulator (SOI) nanowires. This innovative structure enhances both driving and addressability, while minimizing decoherence fields for electron spin qubits. Charge noise spectra show sub-1 · 10-6e2fflz values at 1 Hz, demonstrating a low noise impact from Cogates. Our double dot experimental data show stable quantum confinement at 10 mK and full multi-gate FET functionality. Based on calibrated magnetic simulations, we investigate and discuss the advantages of exploiting simultaneously elecmcal and ferromagnetic properties of gates. The record small achieved dot-magnet distance is in the range of 5 to 12 nm, with a footprint of the magnetic gates of 30x70nm2 on dots area, the smallest reported to date on a qubit structure, with a Rabi frequency of 282 MHz and qubit addressability of 1.069 GHz. This novel architecture paves the way to large-scale integration of qubits arrays with unprecedented magnetic control.