Photoreflectance study of the electronic structure of Si-doped InyGa1−yAs1−xNx films with x < 0.012

The electronic structure of Si-doped InyGa1−yAs1−xNx films on GaAs substrates, grown by nitrogen-plasma-assisted MBE, was examined by photoreflectance (PR) spectroscopy at temperatures between 20 K and 300 K. The measured critical-point energies were described by a band anti-crossing (BAC) model with the addition of a Burstein-Moss band-filling term. The energy difference between the nitrogen impurity level and conduction band edge was (0.3004 ± 0.0101) eV at 20 K, and (0.3286 ± 0.0089) eV at 295 K; the BAC interaction parameter was (2.588 ± 0.071) eV. It was inferred from the magnitude of the Burstein-Moss shift that the near-surface carrier concentration, probed by PR, is reduced from the bulk (Hall effect) carrier concentration by a reduction factor of 0.266 ± 0.145. The effect of strain on the PR energies was too small to observe. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)