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X‐ray characterization of physical‐vapor‐transport‐grown bulk AlN single crystals
Author(s) -
Wicht Thomas,
Müller Stephan,
Weingärtner Roland,
Epelbaum Boris,
Besendörfer Sven,
Bläß Ulrich,
Weisser Matthias,
Unruh Tobias,
Meissner Elke
Publication year - 2020
Publication title -
journal of applied crystallography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.429
H-Index - 162
ISSN - 1600-5767
DOI - 10.1107/s1600576720008961
Subject(s) - materials science , dislocation , crystal (programming language) , crystallography , wafer , full width at half maximum , void (composites) , diffraction , condensed matter physics , crystal growth , molecular physics , optics , chemistry , composite material , optoelectronics , physics , computer science , programming language
AlN slices from bulk crystals grown under low thermomechanical stress conditions via the physical vapor transport (PVT) method were analyzed by X‐ray methods to study the influence of the growth mode on the crystal quality. Defect types and densities were analyzed along axial [000 1 ] as well as lateral growth directions. X‐ray diffraction (0 1 10) rocking‐curve mappings of representative wafer cuts reveal a low mean FWHM of 13.4 arcsec, indicating the generally high crystal quality. The total dislocation density of 2 × 10 3 cm −2 as determined by X‐ray topography is low and dislocations are largely threading edge dislocations of b = 1/3⟨11 2 0⟩ type. The absence of basal plane dislocations in homogeneous crystal regions void of macroscopic defects can be linked to the low‐stress growth conditions. Under the investigated growth conditions this high crystal quality can be maintained both along the axial [000 1 ] direction and within lateral growth directions. Exceptions to this are some locally confined, misoriented grains and defect clusters, most of which are directly inherited from the seed or are formed due to the employed seed fixation technique on the outer periphery of the crystals. Seed‐shaping experiments indicate no apparent kinetic limitations for an enhanced lateral expansion rate and the resulting crystal quality, specifically with regard to the growth mode on a ‐face facets.