Photoreflectance studies of (Al)Ga- and N-face AlGaN/GaN heterostructures

C. Buchheim, A. T. Winzer, R. Goldhahn, G. Gobsch, O. Ambacher, A. Link, M. Eickhoff, M. Stutzmann

Research output: Contribution to journalConference articlepeer-review

18 Scopus citations


Photoreflectance studies were carried out on AlxGa 1-xN/GaN heterostructures confining high-mobility polarization-induced two-dimensional electron gases. By analyzing the Franz-Keldysh oscillations for samples with (Al)Ga- and N-face polarity, we obtained values for the surface electric field up to F = 380 kVcm-1 at room temperature. Taking into account spontaneous and piezoelectric polarization, the density of charged surface states and the bare surface potential are estimated. The results unambiguously prove the presence of donor- and acceptor-like surface states for samples with (Al)Ga- and N-face polarity, respectively. A change of the electric field was observed upon the exposure of the surface to a polar liquid, demonstrating the applicability of these structures for chemical sensors.

Original languageEnglish
Pages (from-to)155-158
Number of pages4
JournalThin Solid Films
Issue number1
StatePublished - 22 Feb 2004
EventProceedings of Symposium M on Optical and X-Ray Metrology - Strasbourg, France
Duration: 10 Jun 200313 Jun 2003


  • GaN
  • Heterostructure
  • Photoreflectance
  • Polarization
  • Surface states


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