Undoped 2D Electron systems as a tool for optimising MBE growth (SP Workshop)

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• Mr Ben Ramsay, University of Cambridge, Semiconductor Physics Group
• Wednesday 11 May 2016, 14:15-15:15
• Mott Seminar Room (Mott Building Room 531), Cavendish Laboratory.

If you have a question about this talk, please contact Teri Bartlett.

The MBE growth of ultra-high-quality GaAs/AlGaAs epilayer structures has enabled the discovery of many novel physical phenomena, for example the fractional quantum Hall effect (FQHE) in two- dimensional electron systems (2DESs). In order to attain the highest electron mobilities (in excess of 107 cm2V-1s-1), it is necessary to understand and limit the dominant sources of disorder during the wafer growth. These include both intentional (i.e. doping) and unintentional charged impurities, interface roughness and surface defect states, all of which cause electron scattering.

The electron mobility in a modulation-doped 2DES is dominated by doping impurities. By contrast the electron mobility in an undoped is dominated by unintentional background impurities and interface roughness. By measurement and numerical modelling of the mobility versus density characteristics of an undoped wafer, it is possible to determine the concentration of background impurities and the characteristic length and height scales of the roughness. Therefore these systems are a powerful tool for assessment of the cleanliness of an MBE chamber and optimisation of growth conditions.

This talk is part of the Semiconductor Physics Group Seminars series.

This talk is included in these lists:

• All Cavendish Laboratory Seminars
• All Talks (aka the CURE list)
• Centre for Health Leadership and Enterprise
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• ME Seminar
• Mott Seminar Room (Mott Building Room 531), Cavendish Laboratory
• Neurons, Fake News, DNA and your iPhone: The Mathematics of Information
• School of Physical Sciences
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• Thin Film Magnetic Talks

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