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Abnormal Grain Growth in AlScN Thin Films Induced by Complexion Formation at Crystallite Interfaces
Author(s) -
Sandu Cosmin Silviu,
Parsapour Fazel,
Mertin Stefan,
Pashchenko Vladimir,
Matloub Ramin,
LaGrange Thomas,
Heinz Bernd,
Muralt Paul
Publication year - 2019
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.201800569
Subject(s) - nucleation , crystallite , materials science , grain boundary , wurtzite crystal structure , crystallography , low energy electron microscopy , thin film , grain growth , substrate (aquarium) , surface energy , condensed matter physics , surface diffusion , sputter deposition , chemical physics , electron microscope , hexagonal crystal system , grain size , sputtering , microstructure , nanotechnology , composite material , chemistry , metallurgy , optics , physics , organic chemistry , oceanography , adsorption , geology
Sputter deposited Al (1– x ) Sc x N thin films with a Sc content from x = 0 to 43 at% are investigated by electron microscopy in order to study and explain the formation and growth of abnormally oriented grains (AOG). It is found that the latter did not nucleate at the interface with the substrate, but at high energy grain boundaries, at which systematically higher Sc concentrations are detected. The AOGs are thus formed during the growth of c‐textured grains. They grow faster than those, and finally protrude from the c‐textured film surface, having at their end a pyramidal shape with three facets of a hexagonal wurtzite crystal: one (0001) and two (11 2 ¯ 0) facets. Process conditions favoring less compact grain boundaries, and lower surface diffusion across grain boundaries are thought to promote nucleation of AOGs. Finally, a 4‐step growth mechanism explaining the nucleation from a Sc‐rich complexion and proliferation of AOGs with increasing film thickness is proposed.