Candidate:
Burak
Tekcan
Title:
III-V
Semiconductor
Nanowire
Avalanche
Photodiodes
Date:
December
9,
2022
Time:
10:00
AM
Place:
EIT
3141
Supervisor(s):
Ban,
Dayan
-
Reimer,
Michael
Abstract:
Detecting
single
photons
with
high
efficiency
and
timing
resolution
opens
up
new
possibilities
for
various
technologies
such
as
light
detection
and
ranging
(LIDAR),
ultra-long
distance
communications,
singlet
oxygen
detection
for
cancer
treatment,
optical
coherence
tomography
(OCT)
and
quantum
information.
The
image
quality
in
a
spectroscopy
system
for
analysis
of
biological
tissue
or
precision
of
LIDAR
systems
can
be
significantly
improved
with
quantum
sensing
technologies.
Moreover,
OCT
imaging
systems
can
be
improved
for
higher
resolution
mapping
of
human
retina
leading
to
early
detection
of
blinding
diseases.
Detecting
single
photons
can
also
enable
high
speed
quantum
communication
technologies
by
improving
the
detection
speed.
Currently,
the
two
leading
technologies
for
quantum
detection
are
superconducting
nanowires
and
semiconductor
avalanche
photodiodes.
Superconducting
nanowires
have
excellent
detection
efficiencies
(>90%)
and
precise
timing
resolution
(<50
ps);
however,
they
require
cryogenic
temperatures
and
bulky
compressors
and
pumps
to
operate
(typically
<4K),
which
results
in
a
huge
limitation
for
practical
and
portable
applications.
In
contrast,
semiconductor
based
single
photon
avalanche
diode
(SPAD)
technology
exists
for
portable
applications,
nonetheless,
the
high
efficiency
is
achieved
for
a
small
wavelength
range
and
at
the
cost
of
timing
resolution
(200-500
ps).
This
work
offers
a
novel
approach
to
improve
the
quantum
efficiency
of
semiconductor
based
photodiodes
by
taking
advantage
of
remarkable
optical
and
electrical
properties
of
nanowires.
Embedding
photodiode
architecture
in
nanowire
arrays
show
great
promise
leading
the
way
towards
next
generation
quantum
detectors.
In
this
work,
III-V
semiconductor
nanowire
arrays
exhibit
near-unity
absorption
for
an
unprecedented
wavelength
range
when
the
nanowire
shape
and
geometry
is
optimized.
Previously
developed
InP
based
nanowire
quantum
sensors
exhibited
single
photon
sensitivity
and
fast
response
with
0.6ns
rise
time
and
only
17ps
timing
jitter
at
room
temperature.
In
this
thesis,
the
aim
is
to
extend
the
single
photon
sensitivity
towards
near
infrared
and
short-wave
infrared
wavelengths
by
using
InGaAs
as
an
active
material.
Our
novel
nanowire
pin
photodiodes
based
on
InGaAs
displayed
remarkable
improvement
in
quantum
efficiency
(>85%)
including
the
wavelength
band
“valley
of
death”
(800-1000nm)
where
OCT
imaging
operates
for
enhanced
sensitivity
and
axial
resolution
for
eye
imaging.
We
also
built
nanowire
based
avalanche
photodiodes
to
introduce
gain
mechanism
detecting
single
photons
efficiently
at
short
wave
infrared.
The
thesis
describes
the
approach
to
design
nanowire
arrays
for
near
unity
absorption,
the
process
to
fabricate
those
structures
in
a
cleanroom
and
electrical
and
optical
characterization
of
fabricated
nanowire
arrays
demonstrating
high
quantum
efficiency
and
fast
response.
Friday, December 9, 2022 10:00 am
-
10:00 am
EST (GMT -05:00)