Fig. 4: Impact of charged impurities in quantum dots below a rough Si/SiO₂.

a A random distribution of negative charge impurities with typical industry-level densities of ~4 × 10¹⁰ nm⁻¹¹⁷. b Variability of the quantum dot wavefunctions of the same dots in Fig. 2c. There is a negative trap close to dot number 2. c, d Atomistic simulations of valley splittings (b) and g-factors (c) of each quantum dot in the 49 dot array, comparing simulations with and without charged traps. We set E_z = 28 meV nm⁻¹ in these simulations (Fig. 2f). In both cases, simulations are performed with the same surface profile (Fig. 1b). e Dispersion of dot centres under the presence of interface roughness and charged traps. f Comparison between the amplitude of the dispersion of dot centres in both scenarios. Box in all figures indicate median (middle line), 25th, 75th percentile (box) and 5th and 95th percentile (whiskers) as well as outliers (single points). Source data of a, c–f are provided in the Source Data file.