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arsine gas (AsH
3
) from the addition of HCl to Zn
3
As
2
, which was then passed
through a hot (220
C) solution of ODE and indium acetate and myristic acid
over a 20 minute period to result in zinc blende InAs particles, in a similar
reaction to that described by the Reiss group.
53
In a similar manner to InP
grown using PH
3
, the generation of AsH
3
rst
5 minutes of particle growth, and was then slower for the remaining duration
of the reaction. Addition of further ODE was also used to drop the solution
temperature and stop the nucleation, allowing a separate and discrete growth
step, although prolonged reaction times resulted in the precipitation of
elemental arsenic. Varying reaction conditions improved the size distribu-
tion and photoluminescence, with the emission being particularly sensitive
to the indium : capping agent ratio. The absorption pro
ow was strongest in the
d
n
1
y
4
n
g
|
3
le showed a clear
excitonic peak at about 700 nm, with emission between
ca.
750 and 800 nm
although the quantum yield was still below 1% and decreased upon pro-
longed oxidation, in contrast to InAs prepared by As(SiMe
3
)
3
. The emission
could be improved by addition of a ZnSe shell, as described in Chapter 5.
2.4 Group III
Antimonides
There are few reports of solution routes to antimonide-based QDs, although
the dehalosilylation reaction is suitable for the synthesis of GaSb nano-
particles.
89
Addition of Sb(SiMe
3
)
3
to a toluene solution of GaCl
3
at room
temperature resulted in an immediate reaction, giving GaSb and Me
3
SiCl
a
-
ed by sublima-
tion at 400
C, giving an antimony-rich sample of nanocrystalline GaSb with
dimensions of 30
er 24 hours re
ux. The resulting materials could be puri
.
40 nm. Although this route does not utilise a capping
agent and no optical properties were reported, it does con
-
rm that the
dehalosilylation reaction is a viable route to these materials.
This route was also extended to the preparation of InSb particles using
In(COOCH
3
)
3
and stearic acid in ODE.
90
er degassing the indium
precursor and capping agents at elevated temperatures, followed by cooling
to 100
C, a solution of Sb(SiMe
3
)
3
in TOP was injected into the reaction
A
ask,
followed by 5 minutes growth and then cooling using an ice bath. Isolation of
the InSb particles was achieved using solvent/non-solvent interactions. The
particles had an absorption edge at
ca.
700
from
the bulk band edge at 0.17 eV (7300 nm) although no excitonic feature was
observed. Near band edge emission was also observed with a maximum at
800 nm. The particles were 3
-
800 nm, a signi
cant shi
13 nm in diameter and crystalline, although no
discussion of the crystal phase was reported.
Zinc blende-structured alloys of InAs
x
Sb
1
x
could be prepared by
combining arsenic and antimony precursors.
91
The particles,
ca.
3nmin
diameter, were prepared by injections of varying amounts of Sb(SiMe
3
)
3
and
As(SiMe
3
)
3
into an ODE solution of In(COOCH
3
)
3
and oleic acid at 300
C,
followed by growth for only 30 minutes at 270
C, resulting in alloyed
particles of InAs
x
Sb
1
x
of varying compositions. Precursor ratios (As : Sb) of
90 : 10, 66 : 33 and 50 : 50 resulted in composition of 97 : 3, 90 : 10 and
-
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