Characterization and suppression of low-frequency noise in Si/SiGe quantum point contacts and quantum dots

Takeda, K.; Obata, T.; Fukuoka, Y.; Akhtar, W. M.; Kamioka, J.; Kodera, T.; Oda, S.; Tarucha, S.
March 2013
Applied Physics Letters;3/25/2013, Vol. 102 Issue 12, p123113
Academic Journal
We report on the effects of a global top gate on low-frequency noise in Schottky gate-defined quantum point contacts (QPCs) and quantum dots (QDs) in a modulation-doped Si/SiGe heterostructure. For a relatively large top gate voltage, the QPC current shows frequent switching with 1/f2 Lorentzian type charge noise. As the top gate voltage is decreased, the QPC pinch-off voltage becomes less negative, and the 1/f2 noise becomes rapidly suppressed in a homogeneous background 1/f noise. We apply this top-gating technique to double QDs to stabilize the charge state for the electron number down to zero.


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