Abstract
Hot electron transport in
Au
-
Hf
O
2
-
Si
O
2
-
Si
structures with
4
nm
Hf
O
2
and
1.5
nm
Si
O
2
interfacial layer have been investigated by ballistic electron emission spectroscopy (BEES). By controlling the hot electron kinetic energy and injection current, distinctly different barrier heights can be measured. BEES sweeping below
−
5
V
with
1
nA
injection current yields high barrier heights
(
∼
3.8
eV
)
, attributable to the interfacial
Si
O
2
layer. BEES sweeping from
−
6
V
with high injection current (
5
nA
and above) induced localized breakdown of the
Si
O
2
interfacial layer, allowing the barrier height of the
Hf
O
2
layer to be measured
(
∼
1.9
eV
)
. The energy-dependent effective mass of electrons in
Hf
O
2
is also determined by fitting oscillations in the BEES current.