Figure 4: Tunability of the VS via gate-voltage control.
From: Spin-valley lifetimes in a silicon quantum dot with tunable valley splitting
(a) Spin-up probability as a function of magnetic field for VP=1.59 V. The occurrence of a hot-spot minimizes the spin-up fraction and allows one to extract BHS (shaded area) and, in turn, EVS. (b) Pulsed-voltage magnetospectroscopy showing dISET/dVP at N=1→2 transition. A square pulse of amplitude 16 mV at 287 Hz is applied to gate P. The evolution of the energy difference between the singlet state (light grey) and the triplet state (dark grey) allows one to extract BST (dashed line) and, in turn, EVS. (c) Valley splitting as a function of plunger gate voltage (bottom axis) and modulus of interface vertical electric field in the QD (top axis). Blue and red dots show the valley separation (left axis) measured with hot-spot and magneto-spectroscopic techniques, respectively. Error bars indicate standard deviations for the measured values. The linear fit (solid line) indicates a valley tunability of 0.640 meV V−1. Dashed lines are calculations performed via atomistic (purple) and effective mass (green) methods (right axis). Bottom inset: Table comparing calculated and experimental tunabilities. Top inset: TCAD simulation of the conduction band profile at VP=1.4 V in the (x,z) plane. Negative energy region in red reveals where the dot is formed.
