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Quantitative measurements of internal electric fields with differential phase contrast microscopy on InGaN/GaN quantum well structures
Author(s) -
Lohr Matthias,
Schregle Ralph,
Jetter Michael,
Wächter Clemens,
MüllerCaspary Knut,
Mehrtens Thorsten,
Rosenauer Andreas,
Pietzonka Ines,
Strassburg Martin,
Zweck Josef
Publication year - 2016
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.201552288
Subject(s) - electric field , quantum well , piezoelectricity , materials science , optoelectronics , scanning transmission electron microscopy , indium , transmission electron microscopy , wide bandgap semiconductor , light emitting diode , scanning electron microscope , optics , physics , nanotechnology , laser , quantum mechanics , composite material
Abstract Piezoelectric and spontaneous polarization play an essential role in GaN‐based devices. InGaN quantum wells (QWs) in GaN host material, especially grown along the polar c ‐direction, exhibit strong internal fields in the QW region due to the indium‐induced strain. An exact knowledge of the electric fields is essential, since they are one of the factors limiting the performance of green LDs and LEDs. Differential phase contrast in a scanning transmission electron microscope enables direct, local, and quantitative measurements of these electric fields. For a multi‐QW sample, it was possible to determine the piezoelectric field in the range of 43–67 MV m −1 with a resolution of 10 MV m −1 ( ≡ 10 mV nm −1 ).