increase the electronic conductivity by orders of magnitude. In the same time the
material remains superionic conductor with an ionic transference number of t ion > 0.99.
Thus, the crystallographic structure and the superionic properties are preserved, but the
electronic conductivity in the order of σ e ¼ (10
À2
À 10
À3
)σ ion was sufficient to enable
STM imaging and experiments [21]. This approach has allowed to use the full
functionalities of the STM on RbAg 4 I 5 thin films, including imaging, I-z spectroscopy
and Atomic Switch experiments.
Different approach has been used with oxides such as Ta 2 O 5 , HfO 2 and TiO 2 . In a
macroscopic sense they are high-k materials at room temperature and per definition
not suitable for STM. In order to use STM on these materials the thickness of the
studied layers should be reduced down to 3–5 nm and they should be annealed in
vacuum in order to ensure some level of reduction, without reaching the level of
decomposition. After such treatment the samples were able to be studied by scanning
tunnelling microscope using all its analytical modes [29].
Thus, even “non-classical” materials such as insulators and purely ionic conductors can be modified in a way that enables Atomic Switch and in general STM
studies.
4 The Atomic Switch as a Fundamental Approach
for Electrochemical Studies
The atomic switch configuration is providing a unique opportunity to perform
electrochemical studies with highest precision, lateral, mass and charge resolution.
It combines both the technical advantages of the STM (imaging, morphology and
Fig. 1 Macroscopic classification of materials/compounds in respect their transport properties. The
column in the middle shows materials that can be commonly used for STM studies. The other
classes of materials require particular modifications to become suitable for Atomic Switch
experiments
76
I. Valov et al.
material remains superionic conductor with an ionic transference number of t ion > 0.99.
Thus, the crystallographic structure and the superionic properties are preserved, but the
electronic conductivity in the order of σ e ¼ (10
À2
À 10
À3
)σ ion was sufficient to enable
STM imaging and experiments [21]. This approach has allowed to use the full
functionalities of the STM on RbAg 4 I 5 thin films, including imaging, I-z spectroscopy
and Atomic Switch experiments.
Different approach has been used with oxides such as Ta 2 O 5 , HfO 2 and TiO 2 . In a
macroscopic sense they are high-k materials at room temperature and per definition
not suitable for STM. In order to use STM on these materials the thickness of the
studied layers should be reduced down to 3–5 nm and they should be annealed in
vacuum in order to ensure some level of reduction, without reaching the level of
decomposition. After such treatment the samples were able to be studied by scanning
tunnelling microscope using all its analytical modes [29].
Thus, even “non-classical” materials such as insulators and purely ionic conductors can be modified in a way that enables Atomic Switch and in general STM
studies.
4 The Atomic Switch as a Fundamental Approach
for Electrochemical Studies
The atomic switch configuration is providing a unique opportunity to perform
electrochemical studies with highest precision, lateral, mass and charge resolution.
It combines both the technical advantages of the STM (imaging, morphology and
Fig. 1 Macroscopic classification of materials/compounds in respect their transport properties. The
column in the middle shows materials that can be commonly used for STM studies. The other
classes of materials require particular modifications to become suitable for Atomic Switch
experiments
76
I. Valov et al.