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Optical polarization of m ‐plane In‐GaN/GaN light‐emitting diodes characterized via confocal microscope
Author(s) -
Masui Hisashi,
Yamada Hisashi,
Iso Kenji,
Hirasawa Hirohiko,
Fellows Natalie N.,
Speck James S.,
Nakamura Shuji,
DenBaars Steven P.
Publication year - 2008
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.200824044
Subject(s) - confocal , microscope , polarization (electrochemistry) , light emitting diode , diode , wavelength , materials science , optoelectronics , optics , confocal microscopy , microscopy , optical microscope , chemistry , scanning electron microscope , physics
A confocal microscope was applied to characterize near‐field optical polarization of light emission from InGaN‐based light‐emitting diodes prepared on a nonpolar orientation. Detection of stray light was significantly reduced as a result of the confocal technique compared to broad‐area measurements. The confocal measurement required no special sample preparation and obtained data was directly interpretable. A polarization ratio of 0.83 was measured on long‐wavelength emitting devices and was sustained over two orders of magnitude of low current range. Energy shifts and separation of emission peaks for the two polarization components were evaluated to discuss the valence‐band structure. Energy shifts indicated that the topmost band | X 〉 had a heavier effective mass than the lower band | Z 〉. Splitting energy of InGaN was estimated to be 30 meV. Results were consistent with the past reports, thus it was confirmed that the confocal microscope is a valid technique to characterize near‐field optical polarization. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)