12 research outputs found
Maximum-density droplet and charge redistributions in quantum dots at high magnetic fields
Intermediate low spin states in a few-electron quantum dot in the v =< 1 regime
Applied Science
Two-stage kondo effect in a quantum dot at a high magnetic field
We report a strong Kondo effect (Kondo temperature ~ 4K) at high magnetic
field in a selective area growth semiconductor quantum dot. The Kondo effect is
ascribed to a singlet-triplet transition in the ground state of the dot. At the
transition, the low-temperature conductance approaches the unitary limit. Away
from the transition, for low bias voltages and temperatures, the conductance is
sharply reduced. The observed behavior is compared to predictions for a
two-stage Kondo effect in quantum dots coupled to single-channel leads.Comment: 4 pages, 5 figure
InSitu Reduction of Charge Noise in GaAs/AlxGa1-xAs Schottky-Gated Devices
We show that an insulated electrostatic gate can be used to strongly suppress ubiquitous background charge noise in Schottky-gated GaAs=AlGaAs devices. Via a 2D self-consistent simulation of the conduction band profile we show that this observation can be explained by reduced leakage of electrons from the Schottky gates into the semiconductor through the Schottky barrier, consistent with the effect of ‘‘bias cooling.’’ Upon noise reduction, the noise power spectrum generally changes from Lorentzian to 1/f type. By comparing wafers with different Al content, we exclude that DX centers play a dominant role in the charge noise.Kavli Institute of Nanoscience DelftApplied Science
InSitu Reduction of Charge Noise in GaAs/AlxGa1-xAs Schottky-Gated Devices
We show that an insulated electrostatic gate can be used to strongly suppress ubiquitous background charge noise in Schottky-gated GaAs=AlGaAs devices. Via a 2D self-consistent simulation of the conduction band profile we show that this observation can be explained by reduced leakage of electrons from the Schottky gates into the semiconductor through the Schottky barrier, consistent with the effect of ‘‘bias cooling.’’ Upon noise reduction, the noise power spectrum generally changes from Lorentzian to 1/f type. By comparing wafers with different Al content, we exclude that DX centers play a dominant role in the charge noise.Kavli Institute of Nanoscience DelftApplied Science