Distinguishing impurity concentrations in GaAs and AlGaAs, using very shallow undoped heterostructures

W. Y. Mak; K. Das Gupta; H. E. Beere; I. Farrer; F. Sfigakis; D. A. Ritchie

doi:10.1063/1.3522651

Distinguishing impurity concentrations in GaAs and AlGaAs, using very shallow undoped heterostructures

Mesoscale and Nanoscale Physics 2021-09-17 v1

Authors: W. Y. Mak , K. Das Gupta , H. E. Beere , I. Farrer , F. Sfigakis , D. A. Ritchie

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Abstract

We demonstrate a method of making a very shallow, gateable, undoped 2-dimensional electron gas. We have developed a method of making very low resistivity contacts to these structures and systematically studied the evolution of the mobility as a function of the depth of the 2DEG (from 300nm to 30nm). We demonstrate a way of extracting quantitative information about the background impurity concentration in GaAs and AlGaAs, the interface roughness and the charge in the surface states from the data. This information is very useful from the perspective of molecular beam epitaxy (MBE) growth. It is difficult to fabricate such shallow high-mobility 2DEGs using modulation doping due to the need to have a large enough spacer layer to reduce scattering and switching noise from remote ionsied dopants.

Keywords

two-dimensional electron gas undoped heterostructure impurity concentration GaAs AlGaAs mobility molecular beam epitaxy

Cite

@article{arxiv.1007.1019,
  title  = {Distinguishing impurity concentrations in GaAs and AlGaAs, using very shallow undoped heterostructures},
  author = {W. Y. Mak and K. Das Gupta and H. E. Beere and I. Farrer and F. Sfigakis and D. A. Ritchie},
  journal= {arXiv preprint arXiv:1007.1019},
  year   = {2021}
}

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4 pages, 5 eps figures

Distinguishing impurity concentrations in GaAs and AlGaAs, using very shallow undoped heterostructures

Abstract

Keywords

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