Silicon quantum dot devices with a self-aligned second gate layer

TL;DR

This paper presents silicon quantum dot devices with a self-aligned dual-gate structure, enabling precise control of hole spins and revealing key spin properties relevant for quantum computing.

Contribution

It introduces a novel self-alignment fabrication technique for silicon quantum dots with two gate layers, enhancing device precision and spin control capabilities.

Findings

Observation of current rectification due to Pauli spin blockade

Determination of hole g-factor approximately 1.6

Measurement of spin-orbit coupling strength around 0.27 meV

Abstract

We implement silicon quantum dot devices with two layers of gate electrodes using a self-alignment technique, which allows for ultra-small gate lengths and intrinsically perfect layer-to-layer alignment. In a double quantum dot system, we investigate hole transport and observe current rectification due to Pauli spin blockade. Magnetic field measurements indicate that hole spin relaxation is dominated by spin-orbit interaction, and enable us to determine the effective hole $g$-factor $\simeq1.6$. From an avoided singlet-triplet crossing, occurring at high magnetic field, the spin-orbit coupling strength $\simeq0.27$meV is obtained, promising fast and all-electrical spin control.