Optical Polarization Anisotropy in Strained A Plane GaN Films on R Plane Sapphire

Ghosh, Sandıp
Mısra, Pranob
Grahn, Holger T
İmer, Muhsine Bilge
Nakamura, Shujı
Denbaars, Steven P
Speck, James S
We have investigated a [112¯0]-oriented A-plane GaN film on R-plane sapphire, where the c axis of GaN lies in the film plane, by polarized photoreflectance (PR) spectroscopy. Near the fundamental energy gap of GaN, the PR spectrum with the probe light polarized perpendicular to the c axis exhibits one feature corresponding to a single transition labeled T1. For a polarization parallel to c axis, two different features labeled T2 and T3 are observed at higher energies than the transition T1. In order to explain the origin of these three features, we compare the measured energies with calculations of the transition energies and oscillator strengths of the three band-to-band transitions of GaN near its fundamental gap for an anisotropic in-plane strain in the A plane. The analysis shows that the observed transition energies and polarization properties of the three transitions can be explained by the presence of an overall compressive, anisotropic in-plane strain in the film. The authors would like to thank O. Brandt for many useful discussions and M. Ramsteiner for the Raman measurements. One of the authors (S.G.) acknowledges the hospitality of the Paul Drude Institute during the course of this work.
Citation Formats
S. Ghosh et al., “Optical Polarization Anisotropy in Strained A Plane GaN Films on R Plane Sapphire,” presented at the 6th International Conference on Nitride Semiconductors (ICNS), (29 Ağustos-02 Eylül 2005), Bremen, Almanya, 2005, Accessed: 00, 2021. [Online]. Available: https://hdl.handle.net/11511/73749.