AVS 2012 Poster v3 (final version)
Transcript of AVS 2012 Poster v3 (final version)
Interfacial properties of atomic layer deposited TiO2 films on InAs (100) surfaces
ALD of TiO2 on etched InAs surfaces
Conclusions
Native oxide consumption is verified during ALD of TiO2 on InAs (100)
surfaces.
In oxides “bubble” to surface of TiO2 films during the deposition.
Native oxide consumption rate increases as deposition temperature is
raised during the deposition of TiO2 on InAs (100) and GaAs (100)
surfaces.
NSF CAREER award (DMR-0846445)
Materials and Devices for Information Technology (MDITR) STC
(DMR-0120967)
Dr. Karen Gaskell (UMD) for taking the XPS data
ALD of TiO2 on native oxide InAs surfaces
Liwang Ye, Theodosia Gougousi Department of Physics , UMBC
Practically sharp interface is obtained after the deposition of TiO2 on HF
and NH4OH etched InAs (100) surfaces
The deposition of high-κ dielectrics on III-V semiconductors has been under intensive
study due to its potential applications in metal-oxide-semiconductor field-effect
transistors (MOSFET). The interface plays an important role in improving the
performance of the semiconductor devices. Consumption of native oxides has been
demonstrated for Atomic Layer Deposition (ALD) of metal oxides on III-V substrates
when amide precursors are used. In this work we investigate the deposition and
interfacial properties of TiO2 on InAs.
UMBC UMBC
Temperature dependence of the
native oxide consumption
Starting surfaces: HF or NH4OH etched InAs (100) surfaces.
Deposition Temperature: 200°C
TiO2 film thickness: ~2.2 nm
Starting surfaces: Degreased native oxide InAs (100) surfaces.
Deposition Temperature: 100~250°C
Precursors: Tetrakis dimethyl amino titanium (TDMATi) and H2O
Starting surfaces: Degreased native oxide InAs (100) surfaces
Deposition temperature: 200°C
Native oxides are consumed gradually.
In oxides “bubble” to the surface of the TiO2 films.
46 44 42 40
As-In
AsOx
As2O3As2O5
As 3d
20 19 18 17 16 15
In 4d
In-AsIn2O3
In2Ox
152 148 144 140 136
As 3p
As2O3
As2O5
As-In
AsOx
448 447 446 445 444 443 442
In-As
In-O
In 3d5/2
Inte
ns
ity
Binding energy (eV)
Starting
surface
100°C
150°C
200°C
250°C
ALD of ~2nm TiO2 on InAs (100) surfaces
ALD of ~3nm TiO2 on InAs (100) surfaces
Native oxide consumption rate increases as deposition temperature is
raised.
At 250°C As oxides are almost completely removed; some In oxide left.
~ 1.6 nm
native oxide
InAs
epoxy
TiO2 ~4.3nm
InAs
epoxy
Inte
nsit
y
starting surface after the deposition
HRTEM of ~4.3nm TiO2 on native oxide InAs (100) surfaces
448 447 446 445 444 443
In-AsIn-O
In 3d5/2
24 22 20 18 16 14
In 4d
In-AsIn2OxIn2O3
O2s
45 40 35 30
As 3d
As-InAs2O3As2O5
Ti 3p
152 148 144 140 136
As 3p
As-InAs2O3
As2O5
Sta
rting
su
rfac
es
~
2.0
nm
TiO
2
~3.7
nm
TiO
2
~6.4
nm
TiO
2
~3.0
nm
TiO
2
~6.4
nm
TiO
2
Sp
utte
red
Inte
ns
ity
Binding energy (eV)
Native oxide evolution during TiO2 deposition
Introduction
Formation of a practically sharp interface is verified by HRTEM.
Substrate
Native oxide
TiO2
(a) (b) (c) (d)
(a)Starting surface: native oxide covered InAs (100) surface
(b)During the deposition: both As and In oxides are consumed gradually;
In oxides diffuse gradually through the TiO2 film and accumulate on its
surface.
(c) Interface is almost free of native oxides. Some In oxides remain on
the topmost layer of the TiO2 film.
(d)Remaining surface In oxides are removed by sputtering.
Starting surfaces: Degreased native oxide GaAs (100) surfaces
Deposition temperature: 100~250°C
~2nm TiO2 on GaAs ~3nm TiO2 on GaAs
ALD of TiO2 on GaAs (100) surfaces
Native oxide consumption rate increases as deposition temperature is
raised.
At 250°C As oxides are almost complete removed; some Ga oxide left.
Acknowledgements
45 40 35
As 3d
As2O5
As2O3
As-In
Ti 3p
448 447 446 445 444 443
In-O
In-As
In 3d5/2
24 22 20 18 16 14
In 4d
In2O3
In2Ox
In-As
O 2s
HF
etc
he
d
+ 2
.2 n
m T
iO2
As
rec
eiv
ed
InA
s (1
00
) N
H4 O
H e
tch
ed
+ 2
.2 n
m T
iO2
Binding energy (eV)
Inte
nsit
y
152 148 144 140 136
As 3p
As-InAs2O3
As2O5
48 46 44 42 40
As 3d
As2O5As2O3
As-Ga
AsOx
22 21 20 19 18
Ga-AsGa2O
Ga2O3
Ga 3d
46 44 42 40
As 3d
As2O5 As2O3AsOx
As-Ga
Inte
ns
ity
Binding energy (eV)
100°C
150°C
200°C
250°C
22 21 20 19 18
Ga-AsGa2OGa2O3
Ga 3d
Starting
surface
46 44 42 40
As2O5As2O3
AsOx
As-In
As 3d
152 148 144 140 136
As 3p
As2O5
As2O3As-In
AsOx
447 446 445 444 443 442
In-AsIn-O
In 3d5/2
20 19 18 17 16 15
In 4d
In2O3
In2Ox
In-As
Binding energy (eV)
100°C
150°C
200°C
250°C
Starting
surface