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SUMMARY:Versatile ‘Quantum Multiplexing’ for Nanoelectronic Applicatio
 ns - Dr Luke Smith\, Cavendish Laboratory\, University of Cambridge
DTSTART:20140827T131500Z
DTEND:20140827T141500Z
UID:TALK53985@talks.cam.ac.uk
CONTACT:Teri Bartlett
DESCRIPTION:It is highly advantageous to increase the number of nanostruct
 ure devices on a single semiconductor chip\, for high through-put testing.
  \n\nThere have been several recent advances in this area [1 – 3]\, moti
 vated by the goal of creating a scalable architecture for possible quantum
  computing applications. We have developed an on-chip multiplexing techniq
 ue which significantly increases the number of devices that can be located
  on a single chip. This was used to measure an array of 256 split gates on
  a GaAs/AlGaAs high electron mobility transistor (HEMT)\, during one coold
 own in a Cryostat\; the largest number of such devices on an individual ch
 ip to date [1].\n\nSo far\, the multiplexer has been used to perform three
  important tests of the suitability of nanostructure devices as elements f
 or nanoelectronic or computing architectures. These are: \n\ni) yield anal
 ysis\;\nii) reproducibility of device operation on repeated cooldowns [4]\
 ; and\niii) detailed statistical studies of quantum phenomenon and electri
 cal characteristics [5]. These statistical studies focussed on the ‘0.7 
 structure’\, an anomalous conductance feature of transport through one-d
 imensional systems.\n\nRecently\, a charge-locking technique has been deve
 loped which can be used to sequentially bias a large number of gates\, in 
 order to form complex device structures [6]. This has used to contact an a
 rray of quantum dots. We intend to further extend the multiplexing scheme 
 to measure an array of 256 bar gates on a GaAs/AlGaAs HEMT\, where fluctua
 tions in the electron density across the array can be estimated from the v
 oltage at which electrons are fully depleted from beneath each gate. The u
 niformity of HEMTs is thereby characterized\, to identify wafers which hav
 e a high degree of homogeneity.\n\n[1] H. Al-Taie et al.\, Appl. Phys. Let
 t. 102\, 243102 (2013).\n[2] D. R. Ward et al.\, Appl. Phys. Lett. 102\, 2
 13107 (2013).\n[3] J. M. Hornibrook et al.\, Appl. Phys. Lett. 104\, 10310
 8 (2014).\n[4] H. Al-Taie et al.\, arXiv:1407.5806.\n[5] L. W. Smith et al
 .\, Phys. Rev. B 90\, 045426 (2014).\n[6] R. K. Puddy et al.\, arXiv:1408.
 2872.\n
LOCATION:Mott Seminar Room\, Cavendish Laboratory\, Department of Physics
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