Atomic insights into strain-induced nanoscopic compositional fluctuation in AlGaN quantum well epitaxy
Journal
Scripta Materialia
Journal Volume
266
Start Page
116788
ISSN
1359-6462
Date Issued
2025-09-01
Author(s)
Abstract
Identical UVC light-emitting diode AlGaN growth process was applied on two high-quality AlN buffer layers with different initial dislocation densities. We characterized the AlGaN epi by high-resolution scan transmission electron microscopy (HR-STEM) and atom probe tomography (APT). Geometry phase analysis with HR-STEM revealed the sample grown on the more compressively strained template possesses a more pronounced local lattice constant distortion in the multiple-quantum-well (MQW) region. APT further verified the local lattice distortion originated from the strain-induced Ga segregation in the MQW. The comparative compositional analysis revealed the nanoscopic compositional fluctuation favors further incorporation of Ga during epitaxial growth, which triggered the AlGaN growth front destabilization and new defect nucleation. The 1-D composition profiling from both electron dispersive microscopy and APT suggested nitrogen desorption during the AlGaN stress relaxation.
Subjects
Atom probe tomography
Epitaxy
Nitrides
Scanning/transmission electron microscopy
Stress relaxation
Publisher
Elsevier BV
Type
journal article