Semiconductor Semiconductor Nanostructures II Nanostructures II

Semiconductor Semiconductor Nanostructures IINanostructures II
H.vonKänel
H.vonKänel
H.

von

KänelH.

von

Känel
Laboratorium für Festkörperphysik
Laboratorium für Festkörperphysik
ETHZ
ETHZ
App
lications
App
lications
pppp

Lighting
Lighting


Field effect transistors
Field effect transistors
Sensors
Sensors


Sensors
Sensors
–
–Infrared sensors
Infrared sensors
–
–X
X--ray detectorsray detectors
Semiconductor Nanostructures
PeriodictableofelementsPeriodictableofelements
Periodic

table

of

elementsPeriodic

table

of

elements
Semiconductor Nanostructures
Com
p
arison of wurtzite and zincCom
p
arison of wurtzite and zinc--
p
p
blende structures
blende structures
Semiconductor Nanostructures
GroupIIIGroupIII
--
nitrides
nitrides
Group

IIIGroup

III
nitrides
nitrides


Structural data
Structural data


Fundamental band gaps (direct)
Fundamental band gaps (direct)
Semiconductor Nanostructures
Band structures of AlN
,
GaN and InNBand structures of AlN
,
GaN and InN
,
,
All direct
All direct
bandgap
bandgap
bandgap
bandgap
Semiconductors!
Semiconductors!
Ph.D thesis Alexander Vozny
Ph.D thesis Alexander Vozny
ChernivskiNatlUnivUkraine
ChernivskiNatlUnivUkraine
Chernivski

Natl
.
Univ
.,
UkraineChernivski

Natl
.
Univ
.,
Ukraine
2004
2004
Semiconductor Nanostructures
Variation of bandgap with lattice Variation of bandgap with lattice
parameter
parameter


UV
UV--green group III nitridesgreen group III nitrides


Yellow
Yellow--red zinc blende arsenides red zinc blende arsenides --
p
hos
p
hides
p
hos
p
hides
Semiconductor Nanostructures
pp
pp
M.R. Krames et al., J. Display Technol.
M.R. Krames et al., J. Display Technol. 3
3, 160 (2007)
, 160 (2007)
LEDchipdesignsLEDchipdesigns
LED

chip

designsLED

chip

designs
Semiconductor Nanostructures
M.R. Krames, J. Display Technol. M.R. Krames, J. Display Technol. 3
3, 160 (2007)
, 160 (2007)
pp
--n
j
unctions at e
q
uilibrium and forward bias n
j
unctions at e
q
uilibrium and forward bias
p
p
jq
jq
(a)
(b)
(c)
Semiconductor Nanostructures
Osram
‘
sblueLEDchipsOsram
‘
sblueLEDchips
Osrams

blue

LED

chipsOsrams

blue

LED

chips

1
1 ×
×1 mm1 mm2
2
chip size
chip size
B. Hahn et al.
,
Proc. SPIEB. Hahn et al.
,
Proc. SPIE
Semiconductor Nanostructures


350 mA drive current
350 mA drive current
,
,
Vol. 6910 (2008)
Vol. 6910 (2008)
GaNPLintensityvsTDDGaNPLintensityvsTDD
GaN

PL

intensity

vs
.
TDDGaN

PL

intensity

vs
.
TDD
Theory: J.H. You, J. Appl. Phys. Theory: J.H. You, J. Appl. Phys. 101
101, 023516 (2007)
, 023516 (2007)
Semiconductor Nanostructures
EfficiencydroopEfficiencydroop
Efficiency

droopEfficiency

droop
InGaN/GaN QWInGaN/GaN QW--based 1 based 1 ×
×1 mm1 mm2
2
TFFC
TFFC chipschips
Semiconductor Nanostructures
M.R. Krames et al., J
M.R. Krames et al., J. Display Technol. 3, 2007). Display Technol. 3, 2007)
TimeresolvedPLofthickalloysTimeresolvedPLofthickalloys
Time

resolved

PL

of

thick

alloysTime

resolved

PL

of

thick

alloys
SChichibunaturematerials5810(2006)SChichibunaturematerials5810(2006)
Semiconductor Nanostructures
S
.
Chichibu
,
nature

materials

5
,
810

(2006)S
.
Chichibu
,
nature

materials

5
,
810

(2006)
Inv
e
r
s
i
o
n
do
m
a
in
s
f
o
rm
at
i
o
n in
Ga
NInv
e
r
s
i
o
n
do
m
a
in
s
f
o
rm
at
i
o
n in
Ga
N
esodoasoatoGa
esodoasoatoGa
M. Stutzmann et al.
M. Stutzmann et al.
hl(b)
hl(b)
228
228
p
h
ys. stat. so
l
.
(b)
p
h
ys. stat. so
l
.
(b)

228
228
,
,
505 (2001)505 (2001)


Domain formation due to nucleation of Ga
Domain formation due to nucleation of Ga--face and Nface and N--face grainsface grains


Need well
Need well--defined nucleation stepdefined nucleation step
Semiconductor Nanostructures
AlAl
22
OO
33
surfaceterminationandpolaritysurfaceterminationandpolarity
AlAl
22
OO
33
surface

termination

and

polaritysurface

termination

and

polarity
EpiEpi
eadsapphieisOeadsapphieisO
teminatedteminated

Epi
Epi
-
-r
ead
y
sapphi
r
e

is

O
r
ead
y
sapphi
r
e

is

O
-
-
te
r
minatedte
r
minated


O
O--removal during Highremoval during High--T thermal treatmentT thermal treatment
MSttt
MSttt
lh
lh
ttl(b)
ttl(b)
228
228
505(2001)
505(2001)
Semiconductor Nanostructures
M
.
St
u
t
zmann e
t

M
.
St
u
t
zmann e
t
a
l
., p
h
ysa
l
., p
h
ys. s
t
a
t
. so
l
.
(b)
. s
t
a
t
. so
l
.
(b)

228
228
,
505

(2001)
,
505

(2001)
PLinInPLinIn
--
containingalloys
containingalloys
PL

in

InPL

in

In
containing

alloyscontaining

alloys


Spatially varying energy of excited state due to atomic
Spatially varying energy of excited state due to atomic--scale inhomogeneityscale inhomogeneity


ｫ復ｮﵩ說
ｫ復ｮﵩ說


ｫ

復



ｮ



拾ｮｫ

復



ｮ



拾ｮ
Semiconductor Nanostructures
Polarization of strained and unstrained Polarization of strained and unstrained
d
d
nitri
d
es nitri
d
es
Semiconductor Nanostructures
O. Ambacher et al., J. Appl. Phys.
O. Ambacher et al., J. Appl. Phys. 85
85, 3222 (1999)
, 3222 (1999)
PolarizationandbandprofilesPolarizationandbandprofiles
Polarization

and

band

profilesPolarization

and

band

profiles

Left image: Polar (0001) oriented heterostructure
Left image: Polar (0001) oriented heterostructure


Right image: non
Right image: non--polar apolar a--face orientationface orientation
Semiconductor Nanostructures
S. Chichibu, nature materials 5, 810 (2006)
S. Chichibu, nature materials 5, 810 (2006)
GaNcolumnsonAlN/Si(111)GaNcolumnsonAlN/Si(111)
GaN

columns

on

AlN/Si(111)GaN

columns

on

AlN/Si(111)
Potential for columnar LEDs with much higher Potential for columnar LEDs with much higher
lihtttiffii
lihtttiffii
li
g
ht
ex
t
rac
ti
on e
ffi
c
i
ency
li
g
ht
ex
t
rac
ti
on e
ffi
c
i
ency
Semiconductor Nanostructures
SensitivityofthehumaneyeSensitivityofthehumaneye
Sensitivity

of

the

human

eyeSensitivity

of

the

human

eye

︺不ｮ︺不ｮ

︺

﹩

ｮ︺

﹩

ｮ

Gray: day vision
Gray: day vision
Semiconductor Nanostructures
CIEchromaticitydiagramCIEchromaticitydiagram
CIE

chromaticity

diagramCIE

chromaticity

diagram
CIE = Commission Internationale de l‘EclairageCIE = Commission Internationale de l‘Eclairage
Semiconductor Nanostructures
BlueBlue--pumped YAG phosphorpumped YAG phosphor
R


Pump wavelength 460 nm
Pump wavelength 460 nm


LER decreases with blue leakage!
LER decreases with blue leakage!
Semiconductor Nanostructures
M.R. Krames, J. Display Technol.
M.R. Krames, J. Display Technol. 3
3, 160 (2007)
, 160 (2007)
Chromaticity for blueChromaticity for blue--pumped YAGpumped YAG
y


CCT
CCT ~ 5000 K for 35 % blue leakage (LER = 328 lm/W)~ 5000 K for 35 % blue leakage (LER = 328 lm/W)


TheoreticalmaximumLES
~
283lm/WatCRI
~
80TheoreticalmaximumLES
~
283lm/WatCRI
~
80
Theoretical

maximum

LES

283

lm/W

at

CRI

80Theoretical

maximum

LES

283

lm/W

at

CRI

80
Semiconductor Nanostructures
M.R. Krames, J. Display Technol.
M.R. Krames, J. Display Technol. 3
3, 160 (2007)
, 160 (2007)
MaximumdownMaximumdown
--
conversionefficiency
conversionefficiency
Maximum

downMaximum

down
conversion

efficiency

conversion

efficiency

CE
=
(PCE
=
(P
lk
lk
+P
+P
)/P
)/P
LED
LED
CE(P
CE(P
l
ea
kl
ea
k
+P
+P
conv
conv
)/P
)/P
LED
LED
MRKramesetalJDisplayTechnol3160(2007)
MRKramesetalJDisplayTechnol3160(2007)
M
.
R
.
Krames

et

al
.,
J
.
Display

Technol
.
3
,
160

(2007)M
.
R
.
Krames

et

al
.,
J
.
Display

Technol
.
3
,
160

(2007)
Semiconductor Nanostructures
N
ea
r
ba
n
d

edge
PL
o
f
a
ll
oys
N
ea
r
ba
n
d

edge
PL
o
f
a
ll
oys
eabadedgeoaoyseabadedgeoaoys
S. Chichibu, nature materials 5, 810 (2006)S. Chichibu, nature materials 5, 810 (2006)
Semiconductor Nanostructures
QuantumefficienciesofHBLEDsQuantumefficienciesofHBLEDs
Quantum

efficiencies

of

HBLEDsQuantum

efficiencies

of

HBLEDs
JMPhilliLJMPhilliL
&PhtRi1N42007&PhtRi1N42007
J
.
M
.
Philli
ps,
L
aser
J
.
M
.
Philli
ps,
L
aser
&

Ph
o
t
on
R
ev
i
ew
1
,
N
o.
4
,
2007&

Ph
o
t
on
R
ev
i
ew
1
,
N
o.
4
,
2007
Semiconductor Nanostructures
MaximumLERforRYGB(CCT
=
3000K)MaximumLERforRYGB(CCT
=
3000K)
Maximum

LER

for

RYGB

(CCT

3000

K)Maximum

LER

for

RYGB

(CCT

3000

K)

All linewidths 1 nm
All linewidths 1 nm


CCT = 3000 K
CCT = 3000 K
JM
JM
PhillipsetalLaser&PhotonRev1307(2007)
PhillipsetalLaser&PhotonRev1307(2007)
J
.
MJ
.
M
.
Phillips

et

al
.,
Laser

&

Photon

Rev
.
1
,
307

(2007)
.
Phillips

et

al
.,
Laser

&

Photon

Rev
.
1
,
307

(2007)
Semiconductor Nanostructures
SchemeofGaNSchemeofGaN
HEMTHEMT
Scheme

of

GaNScheme

of

GaN
--
HEMT
HEMT
Semiconductor Nanostructures
SheetchargedensityatAlGaN/GaNinterfacesSheetchargedensityatAlGaN/GaNinterfaces
Sheet

charge

density

at

AlGaN/GaN

interfacesSheet

charge

density

at

AlGaN/GaN

interfaces
O. Ambacher et al., J. Appl. Phys. 85, 3222 (1999)O. Ambacher et al., J. Appl. Phys. 85, 3222 (1999)
Semiconductor Nanostructures
AlAl
GaGa
N/GaNheterostructureN/GaNheterostructure
AlAl
0.090.09
Ga
Ga
0.91
0.91
N/GaN

heterostructureN/GaN

heterostructure


Sheet electron density 2.12
Sheet electron density 2.12 ×
×101012
12
cm
cm-
-2 2 at 4 K
at 4 K


Mobilit
y
60‘000 cmMobilit
y
60‘000 cm
2
2/Vs at 4
K
/Vs at 4
K
y
y
C.R. Elsass et al., Jap. J. Appl. Phys. 39, L1023 (2000)
C.R. Elsass et al., Jap. J. Appl. Phys. 39, L1023 (2000)
Semiconductor Nanostructures
ComparisonofHEMTsComparisonofHEMTs
Comparison

of

HEMTsComparison

of

HEMTs
FSchwierzTUIlmenau2003FSchwierzTUIlmenau2003
Semiconductor Nanostructures
F
.
Schwierz
,
TU

Ilmenau

2003F
.
Schwierz
,
TU

Ilmenau

2003
Com
p
arison of trans
p
ort
p
ro
p
ertiesCom
p
arison of trans
p
ort
p
ro
p
erties
pppp
pppp
Typical room temperature data for important interfaces
Typical room temperature data for important interfaces
Semiconductor Nanostructures
Band structures of Si
,
Ge Band structures of Si
,
Ge
,
,
and
and α
α-
-SnSn
Empirical pseudopotential method, Chelikowski and Cohen 1976
Empirical pseudopotential method, Chelikowski and Cohen 1976
Semiconductor Nanostructures
Semiconductor Nanostructures
Band structures of Band structures of tetrahedrallytetrahedrally
bddidt
bddidt
b
on
d
e
d
sem
i
con
d
uc
t
ors
b
on
d
e
d
sem
i
con
d
uc
t
ors
Note the close similarity of the Ge band structure
Note the close similarity of the Ge band structure
with that of GaAs around
with that of GaAs around Γ
Γ
Semiconductor Nanostructures
G
e
u
n
d
er
b
i
a
xi
a
l str
a
in
G
e
u
n
d
er
b
i
a
xi
a
l str
a
in
GudbaaaGudbaaa
M.V. Fischetti & S.E. Laux, J. Appl. Phys. 80, 2234 (1996)
Semiconductor Nanostructures
Improved hole transport: compressive strainImproved hole transport: compressive strain
E
unstrained
compressively strained
E
k
E
k
k
k
HH
LH
SO
■■
Strain lifts HH
Strain lifts HH--LH degeneracyLH degeneracy
SO
■
■
Heavy holes become lighter
Heavy holes become lighter
■
■
䅮瑩
䅮瑩
-
-
捲潳獩湧睩瑨䱈扡湤汥慤lto湯n
捲潳獩湧睩瑨䱈扡湤汥慤lto湯n
-
-
灡牡扯汩捩瑹
灡牡扯汩捩瑹
■
■
䅮瑩
䅮瑩
捲潳獩湧

睩瑨

䱈

扡湤

汥慤l

瑯

湯n捲潳獩湧

睩瑨

䱈

扡湤

汥慤l

瑯

湯n
灡牡扯汩捩瑹
灡牡扯汩捩瑹
卥Si捯湤畣瑯爠乡湯獴牵捴畲敳
Modulation do
p
ed strained Ge Modulation do
p
ed strained Ge
p
p
quantum wells
quantum wells
Tpicalstctesedfohighmobilitholetanspot
Tpicalstctesedfohighmobilitholetanspot
Semiconductor Nanostructures
T
y
pical

st
ru
ct
ur
e
u
sed

fo
r
high

mobilit
y
hole

t
r
anspo
r
tT
y
pical

st
ru
ct
ur
e
u
sed

fo
r
high

mobilit
y
hole

t
r
anspo
r
t
Record hole mobilit
y
of Ge
q
uantum well Record hole mobilit
y
of Ge
q
uantum well
yq
yq
B. Rössner et al., APL
B. Rössner et al., APL 84
84, 3058 (2004)
, 3058 (2004)
Semiconductor Nanostructures
Most recently (University of Warwick 2012) > 1‘000‘000 cm
Most recently (University of Warwick 2012) > 1‘000‘000 cm
2
2/Vs !
/Vs !
GephotodiodesforIRdetectionGephotodiodesforIRdetection
Ge

photodiodes

for

IR

detectionGe

photodiodes

for

IR

detection
Band gap shift by thermally induced tensile
Semiconductor Nanostructures
strain in Ge on Si
BandgapshiftthroughthermalannealingBandgapshiftthroughthermalannealing
Bandgap

shift

through

thermal

annealingBandgap

shift

through

thermal

annealing
Extractionof the direct band-gapenergy for the as grown (●)
andannealed(
■
⤱
땭瑨楣t慢獯牰瑩潮l慹敲
慮a

慮湥慬敤

(
■
)

1
땭

瑨楣t

慢獯牰瑩潮

污祥l
Semiconductor Nanostructures
G. Isella et al., Semicond. Sci. Technol.
G. Isella et al., Semicond. Sci. Technol. 22
22, S26 (2007)
, S26 (2007)
CMOSCMOS
--
integratedpixeldetector
integratedpixeldetector
CMOS
CMOS
integrated

pixel

detectorintegrated

pixel

detector
CMOS circuit 2.5 µm, 1 metal, 1 poly process of CNM Barcelona
Semiconductor Nanostructures
R. Kaufmann et al., JAP 110, 023107 (2011)
IR image sensor with integrated Ge IR image sensor with integrated Ge
photodetectors
photodetectors
photodetectors
photodetectors
Semiconductor Nanostructures
R. Kaufmann et al., JAP 110, 023107 (2011)
Absorbed photons vs. XAbsorbed photons vs. X--reay tube voltagereay tube voltage
Semiconductor Nanostructures
CurrentCurrent
--
voltagemeasurements
voltagemeasurements
Current
Current
voltage

measurementsvoltage

measurements
Au wire
A
p
-
Si
A
Ge
Ge
Ge
p-Ge
p
Si
Ge
Ge
Ge
n-Si
Semiconductor Nanostructures
InIn--situ measurements in SEMsitu measurements in SEM--chamberchamber
SEM picture of top contact on individual germanium tower
SEM chamber
A
G
p-Si
Id
tungsten tip
Conductive
tungsten
tip
2
µ
m
GeGeGe
p-
G
e
Vd
I-V characteristics measured in-situ
tungsten
tip
2

µ
m
渭卩
SEM ZeissNvision40
10 µm
Semiconductor Nanostructures
Definition of detector
p
ixelsDefinition of detector
p
ixels
p
p
Semiconductor Nanostructures
H. von Känel, Europhysics News
H. von Känel, Europhysics News 43
43, 18 (2012)
, 18 (2012)