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Optical anisotropy of a ‐plane Al 0.8 In 0.2 N grown on an a ‐plane GaN pseudosubstrate
Author(s) -
Sakalauskas E.,
Wieneke M.,
Dadgar A.,
Gobsch G.,
Krost A.,
Goldhahn R.
Publication year - 2012
Publication title -
physica status solidi (a)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.532
H-Index - 104
eISSN - 1862-6319
pISSN - 1862-6300
DOI - 10.1002/pssa.201100066
Subject(s) - refractive index , materials science , dielectric , sapphire , birefringence , anisotropy , band gap , ellipsometry , optics , redshift , photon energy , analytical chemistry (journal) , condensed matter physics , molecular physics , thin film , laser , chemistry , physics , photon , optoelectronics , nanotechnology , chromatography , quantum mechanics , galaxy
The optical properties of a ‐plane Al 1− x In x N grown by metal‐organic vapor phase epitaxy on an a ‐plane GaN/ r ‐plane sapphire template are reported. X‐ray diffraction yielded an In content of ∼20%. The ordinary and extraordinary dielectric functions (DFs) were obtained by spectroscopic ellipsometry in the spectral range from 1 eV up to 6 eV at room temperature. By fitting the experimentally obtained complex DF, the inter‐band transitions E A and E B , which are allowed for configurations ${\bf E}\bot {\bf c}$ and ${\bf E}||{\bf c}$ , respectively, were determined. A redshift of ∼200 meV is found for the transition E B with respect to transition E A attributed to the optical selection rules. Furthermore, the ordinary and extraordinary refractive indices in the transparent region (below the band gap) are represented in the analytical form. The AlInN alloy shows the positive birefringence and the difference between the extraordinary and ordinary refractive index n e − n o is defined to be 0.068 at photon energy of 3 eV. Finally, the ordinary and extraordinary high‐energy dielectric constants were estimated.