The electronic structure of the SiO2/SiC (0001) interface, buried below SiO2 layers with a thickness from 2 to 4 nm, was explored using soft X-ray angle-resolved photoemission spectroscopy with photon energies between 350 and 1000 eV. The measurements have detected the characteristic k-dispersive energy bands of bulk Silicon Carbide (SiC) below the SiO2 layer without any sign of additional dispersive states, up to an estimated instrumental sensitivity of ≈5 × 109 cm2 eV. This experimental result supports the physical picture that the large density of interface traps observed in macroscopic measurements results from dangling bonds randomized by the SiO2 rather than from Shockley-Tamm surface derived states extending into the bulk SiC.

1.
E.
Nicollian
and
J.
Brews
,
MOS Physics and Technology
(
Wiley-Interscience
,
1982
).
2.
P.
Friedrichs
,
E. P.
Burte
, and
R.
Schorner
, “
Dielectric strength of thermal oxides on 6H-SiC and 4H-SiC
,”
Appl. Phys. Lett.
65
,
1665
(
1994
).
3.
K.
Fukuda
,
M.
Kato
,
K.
Kojima
, and
J.
Senzaki
, “
Effect of gate oxidation method on electrical properties of metal-oxide-semiconductor field-effect transistors fabricated on 4H-SiC C(0001) face
,”
Appl. Phys. Lett.
84
,
2088
(
2004
).
4.
T.
Kimoto
and
J.
Cooper
,
Fundamentals of Silicon Carbide Technology
(
Wiley
,
2014
).
5.
S. G.
Louie
,
P.
Thiry
,
R.
Pinchaux
,
Y.
Pétroff
,
D.
Chandesris
, and
J.
Lecante
, “
Periodic oscillations of the frequency-dependent photoelectric cross sections of surface states: Theory and experiment
,”
Phys. Rev. Lett.
44
,
549
553
(
1980
).
6.
E. E.
Krasovskii
and
W.
Schattke
, “
Angle-resolved photoemission from surface states
,”
Phys. Rev. Lett.
93
,
027601
(
2004
).
7.
P.
Hofmann
,
C.
Søndergaard
,
S.
Agergaard
,
S. V.
Hoffmann
,
J. E.
Gayone
,
G.
Zampieri
,
S.
Lizzit
, and
A.
Baraldi
, “
Unexpected surface sensitivity at high energies in angle-resolved photoemission
,”
Phys. Rev. B
66
,
245422
(
2002
).
8.
V. V.
Afanas'ev
,
M.
Bassler
,
G.
Pensl
, and
M. J.
Schulz
, “
Intrinsic SiC/SiO2 interface states
,”
Phys. Status Solidi A
162
,
321
(
1997
).
9.
M.
Bassler
,
G.
Pensl
, and
V. V.
Afanas'ev
, “
‘Carbon cluster model' for electronic states at SiC/SiO2 interface
,”
Diamond Relat. Mater.
6
,
1472
(
1997
).
10.
K. V.
Emtsev
,
T.
Seyller
,
L.
Ley
,
A.
Tadich
,
L.
Broekman
,
J.
Riley
,
R.
Leckey
, and
M.
Preuss
, “
Electronic properties of clean unreconstructed 6H-SiC(0001) surfaces studied by angle resolved photoelectron spectroscopy
,”
Surf. Sci.
600
,
3845
3850
(
2006
).
11.
C.
Virojanadara
,
M.
Hetzel
,
L.
Johansson
,
W.
Choyke
, and
U.
Starke
, “
Electronic and atomic structure of the 4H-SiC (1-102)-c(2x2) surface
,”
Surf. Sci.
602
,
525
533
(
2008
).
12.
C.
Powell
,
A.
Jablonski
,
I.
Tilinin
,
S.
Tanuma
, and
D.
Penn
, “
Surface sensitivity of Auger-electron spectroscopy and X-ray photoelectron spectroscopy
,”
J. Electron Spectrosc. Relat. Phenom.
98–99
,
1
15
(
1999
).
13.
V.
Strocov
,
T.
Schmitt
,
U.
Flechsig
,
A.
Imhof
,
Q.
Chen
,
J.
Raabe
,
R.
Betemps
,
D.
Zimoch
,
J.
Krempasky
,
X.
Wang
,
M.
Gironi
,
A.
Piazzalunga
, and
L.
Patthey
, “
High-resolution soft x-ray beamline ADRESS at the Swiss Light Source for resonant inelastic X-ray scattering and angle-resolved photoelectron spectroscopies
,”
J. Synchrotron Radiat.
17
,
631
643
(
2010
).
14.
J.
Sołtys
,
J.
Piechota
,
M.
Łopuszynski
, and
S.
Krukowski
, “
A comparative DFT study of electronic properties of 2H-, 4H- and 6H- SiC(0001) and SiC(000-1) clean surfaces: significance of the surface Stark effect
,”
New J. Phys.
12
,
043024
(
2010
).
15.
T.
Seyller
,
K. V.
Emtsev
,
R.
Graupner
, and
L.
Ley
, “
Initial stages of thermal oxidation of 4H-SiC (11–20) studied by photoelectron spectroscopy
,”
Mater. Sci. Forum
457–460
,
1317
1320
(
2004
).
16.
R.
Queiroz
,
G.
Landolt
,
S.
Muff
,
B.
Slomski
,
T.
Schmitt
,
V. N.
Strocov
,
J.
Mi
,
B.
Iversen
,
P.
Hofmann
,
J.
Osterwalder
,
A.
Schnyder
, and
J.
Dil
, “
Sputtering-induced reemergence of the topological surface state in Bi2Se3
,”
Phys. Rev. B
93
,
165409
(
2016
).
17.
E.
Razzoli
,
M.
Kobayashi
,
V. N.
Strocov
,
B.
Delley
,
Z.
Bukowski
,
J.
Karpinski
,
N. C.
Plumb
,
M.
Radovic
,
J.
Chang
,
T.
Schmitt
,
L.
Patthey
,
J.
Mesot
, and
M.
Shi
, “
Bulk electronic structure of superconducting LaRu2P2 single crystals measured by soft-X-ray angle-resolved photoemission spectroscopy
,”
Phys. Rev. Lett.
108
,
257005
(
2012
).
18.
V. N.
Strocov
,
X.
Wang
,
M.
Shi
,
M.
Kobayashi
,
J.
Krempasky
,
C.
Hess
,
T.
Schmitt
, and
L.
Patthey
, “
Soft-X-ray ARPES facility at the ADRESS beamline of the SLS: Concepts, technical realisation and scientific applications
,”
J. Synchrotron Radiat.
21
,
32
44
(
2014
).
19.
V. N.
Strocov
, “
Intrinsic accuracy in 3-dimensional photoemission band mapping
,”
J. Electron Spectrosc. Relat. Phenom.
130
,
65
78
(
2003
).
20.
H.-G.
Junginger
and
W.
van Haeringen
, “
Energy band structures of four polytypes of Silicon Carbide calculated with the empirical pseudopotential method
,”
Phys. Status Solidi
37
,
709
(
1970
).
21.
V. V.
Afanas'ev
,
A.
Stesmans
,
M.
Bassler
,
G.
Pensl
,
M. J.
Schulz
, and
C. I.
Harris
, “
Elimination of SiC/SiO2 interface states by preoxidation ultraviolet-ozone cleaning
,”
Appl. Phys. Lett.
68
,
2141
(
1996
).
22.
K.
Kita
,
R.
Kikuchi
,
H.
Hirai
, and
Y.
Fujino
, “
Control of 4H-SiC (0001) thermal oxidation process for reduction of interface state density
,”
ECS Trans.
64
,
23
(
2014
).
23.
G. Y.
Chung
,
C. C.
Tin
,
J. R.
Williams
,
K.
McDonald
,
M.
Di Ventra
,
S. T.
Pantelides
, and
L.
Feldman
, “
Effect of nitric oxide annealing on the interface trap densities near the band edges in the 4H polytype of silicon carbide
,”
Appl. Phys. Lett.
76
,
1713
(
2000
).

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