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Synthesis and Characterization of Zinc Tin
Nitride Ian Curtin, Paul Quayle, Kathleen
Kash Dept. of Physics, Case Western Reserve
University, Cleveland, Oh 44106
Abstract
Methods
Conclusions
It was also observed in these growths that in
order to saturate the melt with a sufficient
amount of nitrogen, the pressure had to be
lowered a couple of orders of magnitude from
previous attempts into the militorr range. This
was able to be observed by lowering the crucible
height to be able to see the melt during growth.
Further saturation will be possible in the near
future with the installation of a longer quartz
tube, shortening the diffusion length of the
plasma reaching the melt.
ZnSnN2 growths were performed inside a high
vacuum plasma system. A Zn-Sn liquid alloy was
created inside of a crucible and was then exposed
to a 290 W nitrogen plasma at 400º C and held at
a pressure of 7 mtorr for 3 hours. The sample was
then allowed to cool with the nitrogen plasma
still on.
Grwoth
conditions were chosen based on previous
successful growths of InN, as history has shown
materials with similar band gaps form at similar
temperatures.

Zinc Tin Nitride is a semiconducting material
that to date has not been synthesized, but is
predicted to have useful applications in
optoelectric devices. The goal of this experiment
was to conduct the first reported growth of
ZnSnN2, determine its optimal growing
conditions, and aid in design development of the
experimental package. Although we didnt
conclusively grow ZnSnN2 we did gain useful
insight into phase separation and are able to
provide a larger platform of knowledge for future
research.
Unfortunately we werent able to conclusively
grow large ammounts of ZnSnN2. Initial results
did reveal the presence of Zn, Sn, and N in
sample 1and exhibited signs of crystalline
morphology. More in depth analysis is needed to
determine the exact compositions and structures
of the material. We were able to learn a lot
about phase seperation and the ZnSn alloy as it
cools from a homogenous liquid into several
distinct states. Significant advances were also
made in the design of the system allowing for
observation of the melt during the growth period.
This will prove to be important in future growth
runs allowing the experimentalist to vary
parameters while being able to see if a film is
forming. Soon we will be able to install a longer
quartz tube increasing the ammount of ionized
reaching the melt. Due to time constraints I
was not able to fully investigate the optimal
growing conditions. However, this research will
provide a larger platform of knowledge for future
experiments.
Results and Discussion
Introduction Group III nitride semiconductors
(GaN, InN, and AlN) are a widely studied group of
materials that have many applications in
optoelectronic devices. Zn-IV nitride
semiconductors (ZnGeN2, ZnSnN2, and ZnSiN2) have
had very little experimental work done on them
and are constructed by replacing half of the
atoms from a group III nitride with Zn and the
given elements neighbor to the right in the
fourth row of the periodic table. This makes
Zn-IV nitrides analogous to the group III
nitrides both in their bandgaps and crystalline
lattice structure, but have distinct predicted
properties which could make them superior to
their predecessors. To date, ZnSnN2 has yet to be
synthesized or characterized, but could serve as
a stable equivalent to InN.
Phase Separation One question we were faced with
was what happens to the ZnSn alloy as the sample
changes from a liquid to a solid. Thermodynamic
theory suggests that as a eutectic mixture of a
certain composition cools, it will separate from
a homogenous liquid into distinct states of
different compositions, all in equilibrium, that
minimize the Gibbs free energy.
The samples grown were inspected under an
optical microscope and a scanning electron
microscope for sign of crystalline morphology.
Elementary chemical analysis was also performed
by energy dispersive X-ray spectroscopy (EDX).
Sample 1 9 at Zn to 91 at Sn Sample 2 22 at
Zn to 78 at Sn Sample 3 29 at Zn to 71 at
Sn During the growth process, upon exposure to
the nitrogen plasma all samples changed from a
shiny metallic surface to a darker textured
surface. Upon further inspection Sample 1 is the
most likely to have developed trace ammounts of
ZnSnN2. Optical and SEM images showed signs of
crystalline morphology and elementary chemical
analysis showed the presence of Zn, Sn, and N in
the sample.
Acknowledgments I would like to thank Dr. Kash,
Paul Quayle, Eric Blanton, and Jermey Trombley
for their guidance and support during this
project and the NSF REU grant DMR-0850037 grant
for providing funding. Also, Id like to thank
Betty Gaffney for making the program run so
smoothly.
References
1 Paudel TR and Lambrechet WRL. 2008.
First-principles study of phonons and related
ground-state properties and spectra in Zn-IV-N2
compounds. Phys. Rev. B 78115204.
Sample 1 EDX averaged over the surface of sample
showing large amounts of Zinc and Tin and trace
amounts of nitrogen. Its important to note the
layers grown are too small for EDX to accurately
characterize.
Sample 1 Image from optical microscope at 500x.
Displays layering typical of polycrystalline
growth.
Plot of lattice constants vs.band gap energy for
group III nitrides and Zn-IV nitrides. Values for
ZnSnN2 and ZnSiN2 predicted by theory. Values for
ZnGeN2 determined experimentally. 1
Sample 3 SEM imaging and EDX analysis clearly
show how the ZnSn alloy solidifies into two
distinctly different compositions predicted by
the ZnSn binary phase diagram.