New, Germanium - Related Defect in Neutron - Irradiated Gallium Phosphide
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NEW , GERMANIUM - RELATED DEFECT IN NEUTRON - IRRADIATED GALLIUM PHOSPHIDE
J. BARCZYNSKA AND E. Institute
of
Warszawa,
GOLDYS
Experimental
Physics,
Warsaw
University,
Hoza
69,
00-681
Poland
ABSTRACT
GaP crystals 1019
neutrons
resulted 10%
in
of
n
were cm .
The
type
-
observed
discussed.
in
with thermal
isochronal
conductivity
transmuted
absorption spectrum is
irradiated
2
/
Ge
atoms
annealing
of
band
photoconductivity.
at
with a
samples.
neutral
donors.
centered
The
of
up
After
1.4
to
8000C
The similar
the
absorption
*
8000C anneal
Simultaneously
at 1 eV.
origin
fluence
temperatures
irradiated
become
shows a broad
neutrons
the
feature band
is
The band is most likely due to germanium - related defect.
Introduction
Thermal
neutron irradiation
n-type silicon. When
a
The method
semiconductor
lattice
nuclei
into
the
e. g.
Si
nuclei
in
the
atoms into
crystalline
irradiation
is
the of
atoms
move
annealing to
is
a standard
method to produce
irradiated
neutrons.
The
occupying P).
of
with
neutrons
nuclei
nearby
small
undergo
position
of transmutation.
a
the
fraction
in
the
periodic
The
transmuted
nuclei
are
not
in
An
additional
effect
accompanying
structural
defects
various
due
to
and the
optical
properties
removal
of
final,
often
their
of
structure
the
defects
table
substitutional
the
neutron processes
semiconductor. place,
positions
(
substitutional
recoil
takes
of
transformation
defects lower the Fermi level into the midgap region
electrical
course
is
lattice.
formation
The introduced alter
of
transmutes
position
crystal
capture
and annealing
takes advantage of the phenomenon
and
thus
In
the
transmuted and
become
electrically active. Thermal its n-
to IV group the case
neutron
or p-type
irradiation
conductivity,
amphoteric
dopants.
cation or anion sublattice of
GaAs
[1]
and
of
III-V
because After
when it
InSb
[2]
semiconductor
the atoms annealing
the
in
principle
group
moves
or an acceptor.
transmutation
doping
to
transmute
IV group dopant
acts as a donor neutron
leads
from the III
to
In
the
leads
to
predominant donor introduction. We
have
studied
the
thermal
neutron
irradiated
processes for Ga and and P atoms follow the reactions:
Mat. Res. Soc. Symp. Proc. Vol. 163. @1990 Materials Research Society
GaP.
The
transmutation
180
69Ga (n, T) = 7°Ga(g-) • 7°Ge (21 min) 0t
= 1.68 + 0.07 b
th
7 Ga (n,
) =7 Ga(R-) 4 72Ge (14 h)
(r = 4.86 + 0.0.25 b th 31p(n) 32p(f3-) 32S(14.3 d) o-th = 180 + 7 mb. The comparison introduced atoms
of
the transmutation
into GaP
in
thermal
is
Ge.
cross sections
Former
neutron
papers
irradiated
[3]
GaP
shows
indicate
act
as
that the that
all
substitutional
main dopant
transmuted
Ge
donors
Ga
on
site. We report on more complicated behaviour of transmuted Ge in GaP.
Experiment
As
samples
orientation neutral
we
grown
donor
used
by
LEC
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