Tim Bohnen, Gerbe W. G. van Dreumel, Paul R. Hageman, Rienk E. Algra,
Willem J. P. van Enckevort, Elias Vlieg, Marcel A. Verheijen, James H.
Edgar
Growth of
scandium aluminum nitride nanowires on ScN(111) films on 6H-SiC
substrates by HVPE
Abstract:
The formation of ScAlN nanowires on ScN/6H-SiC(0001) by hydride vapor
phase epitaxy (HVPE) was analyzed. The diameters and lengths of the
nanowires were 50 to 150 nm and 1 µm, respectively. The nanowires
had a Al/Sc metal ratio of 95/5 as measured by energy dispersive
analysis of X-rays (EDX). The 4.84 Å unit cell periodicity along
the length of the ScAlN nanowires was similar to that of pure AlN (4.98
Å), as measured by Fourier transforms of high resolution
transmission electron microscopy images of a single nanowire. Only the
(111) and (222) peaks of the ScN continuous film and the (0006) of the
6H-SiC substrate were detected by -2 X-ray diffraction. A tentative
model, based on catalyst-induced growth, is proposed to explain the
unintentional formation of nanowires on the ScN film. This model is
based on the production of volatile Al (possibly AlCl) by the reaction
of the scandium metal source with the alumina reactor tube and
subsequent reaction with hydrogen chloride. This reacts with ammonia in
the deposition zone to create ScAlN nanowires, catalyzed by small ScAl
clusters, which are spontaneously formed on the ScN film before the
nanowire growth.