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Inhomogeneities of InGaN/GaN MOVPE multi quantum wells grown with a two temperatures process studied by transmission electron microscopy
Author(s) -
Kret S.,
Ivaldi F.,
Sobczak K.,
Czernecki R.,
Leszczyński M.
Publication year - 2010
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.200983116
Subject(s) - indium , metalorganic vapour phase epitaxy , materials science , quantum well , transmission electron microscopy , epitaxy , anisotropy , optoelectronics , analytical chemistry (journal) , optics , chemistry , nanotechnology , laser , physics , layer (electronics) , chromatography
The structural investigation of InGaN/GaN:Si multiple quantum well (MQW) samples grown by low‐pressure metal‐organic vapor phase epitaxy (LP‐MOVPE) in a two temperatures (2 T ) process on high‐pressure GaN mono‐crystalline substrates is performed by transmission electron microscopy (TEM). A sample in which barriers and wells were grown at 780 °C is compared with another in which the barriers were deposited at 900 °C and the wells at 730 °C. For both samples the indium composition in the QWs reaches the level of about 20 at.%. The local indium composition was measured through strain measurements by digital processing from the lattice fringes images taken by TEM. Cross‐sectional investigations are performed in two zone axes – [ $1\bar {1}00$ ] and [ $11\bar {2}0$ ] – with the use of axial and off‐axis illumination. During TEM investigations the formation of “false indium clusters ” of the size of 2–4 nm was observed for both samples just after 2 min of LaB6 electron beam illumination at 200 kV. Large lateral fluctuations of indium content in the QWs of the length of 30–130 nm were detected in 2 T sample. The plan view analysis was carried out to characterize the anisotropy of the indium fluctuation inside the QWs.