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Spin and interaction effects in Shubnikov-de Haas oscillations and the quantum Hall effect in GaN/AlGaN heterostructures

Research output: Contribution to journalJournal article

Published

  • W Knap
  • Vladimir Falko
  • E Frayssinet
  • P Lorenzini
  • N Grandjean
  • D Maude
  • G Karczewski
  • B L Brandt
  • J Lusakowski
  • I Grzegory
  • M Leszczynski
  • P Prystawko
  • C Skierbiszewski
  • S Porowski
  • X Hu
  • G Simin
  • M A Khan
  • M S Shur
Journal publication date26/05/2004
JournalJournal of Physics: Condensed Matter
Journal number20
Volume16
Number of pages12
Pages3421-3432
Original languageEnglish

Abstract

We present the results of high magnetic field (up to 30 T) and temperature (50 mK-80 K) dependent transport measurements on a 2DEG in GaN/AlGaN heterojunctions. A high mobility (above 60000 cm(2) V-1 s(-1) at 4 K) 2DEG was obtained by MBE growth of dislocation free GaN and AlGaN layers on semi-insulating bulk GaN substrates. A cyclotron gap and spin splitting are observed. Results from two studies are reported: (i) a tilted field experiment determining the 2DEG g*-factor from the angular modulation of the amplitude of SdH oscillations; (ii) quantum Hall effect measurements determining the activation energies for spin and cyclotron energy gaps at even and odd filling factors. The observed 'cyclotron gap' enhancement is attributed to the effect of electron-electron interaction and it is estimated using the model of a 2D-screened Coulomb potential. The analytic result for the enhancement of the,cyclotron gap' yields an addition to the activation energy, epsilon(even)(x) approximate to kappa(h) over bar omega(c), K = 1.06 roota(2)n(e), which is proportional to the magnetic field and resembles the mass renormalization.