Excited-state spectroscopy in a Si/SiGe quantum dot using charge sensing and pulsed gate voltages
ORAL
Abstract
Excited states in semiconductor quantum dots are often measured using transport spectroscopy, in which the differential conductance through the quantum dot is measured as a function of source-drain bias. Such spectroscopy can be very difficult in the few electron regime. We describe the results of spectroscopy on a Si/SiGe single quantum dot using charge sensing and pulsed gate voltages, thus avoiding the need for transport through the quantum dot. The quantum dot and the charge sensing quantum point contact are defined by top-gates on a Si/SiGe heterostructure. Multiple excited states are observed as a function of increasing amplitude of the voltage pulse. We demonstrate a method to calibrate the ratio of gate voltage to dot energy without using transport through the quantum dot. The result is a quantitative spectroscopy that is efficient even in the absence of any measurable transport through the quantum dot itself. This work was supported in part by ARO and LPS (W911NF-08-1-0482), by NSF (DMR-0805045), by DOD, and by DOE (DE-FG02-03ER46028). This research utilized NSF-supported shared facilities at the University of Wisconsin-Madison.
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Authors
Madhu Thalakulam
University of Wisconsin-Madison, University of Wisconsin - Madison
C. B. Simmons
Department of Physics, University of Wisconsin-Madison, University of Wisconsin-Madison, University of Wisconsin - Madison
B. M. Rosemeyer
University of Wisconsin-Madison, University of Wisconsin - Madison
B. J. Van Bael
University of Wisconsin-Madison, University of Wisconsin - Madison
D. E. Savage
University of Wisconsin Madison, University of Wisconsin-Madison, University of Wisconsin - Madison
Mark Friesen
Department of Physics, University of Wisconsin-Madison, University of Wisconsin-Madison, University of Wisconsin - Madison
Susan Coppersmith, University of Wisconsin
Department of Physics, University of Wisconsin-Madison, University of Wisconsin-Madison, University of Wisconsin - Madison, and Luz J. Martinez-Miranda, University of Maryland
