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Transmission electron microscopy of AlGaAs/GaAs quantum cascade laser structures
Author(s) -
WALTHER T.,
KRYSA A.B.
Publication year - 2017
Publication title -
journal of microscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.569
H-Index - 111
eISSN - 1365-2818
pISSN - 0022-2720
DOI - 10.1111/jmi.12655
Subject(s) - cascade , transmission electron microscopy , quantum cascade laser , laser , optoelectronics , electron , materials science , quantum , transmission (telecommunications) , electron microscope , quantum well , optics , physics , chemistry , nanotechnology , computer science , telecommunications , quantum mechanics , chromatography
Summary Quantum cascade lasers can be efficient infrared radiation sources and consist of several hundreds of very thin layers arranged in stacks that are repeated periodically. Both the thicknesses of the individual layers as well as the period lengths need to be monitored to high precision. Different transmission electron microscopy methods have been combined to analyse AlGaAs/GaAs quantum cascade laser structures in cross‐section. We found a small parabolic variation of the growth rate during deposition, affecting the stack periodicity and a reduced aluminium content of the AlGaAs barriers, whereas their widths as well as those of the GaAs quantum wells agreed with the nominal values within one atomic layer. Growth on an offcut substrate led to facets and steps at the interfaces.