A microplasma printer is employed to deposit thin film patterns of TiO2 by titanium tetra‐isopropoxide and N2/O2 plasma at atmospheric pressure. The setup is adopted to carry out deposition in two configurations, namely under chemical vapor deposition (CVD) and atomic layer deposition (ALD) modes. The properties of TiO2, as well as the patterning resolution, are investigated. The amorphous TiO2 deposited in the CVD mode contains a relatively high level of impurities (residual carbon content of 5–10 at.%) and is characterized by a low refractive index of 1.8. With the ALD mode on the other hand, TiO2 is obtained with a low level of impurities (<1 at.% C and <2 at.% N), a refractive index of 1.98, and a growth per cycle of 0.15 nm. Furthermore, the spatial resolution for a 8‐nm‐thick film is determined by X‐ray photoelectron spectroscopy line scan and found to be equal to 2,000 and 900 µm for the CVD and ALD modes, respectively. This study can be regarded as the first step toward area‐selective CVD and ALD of TiO2 by a microplasma printer, which can be further explored and extended to other material systems.
The dynamic behavior of single bistable Si dopants in the GaAs (110) surface, which switch between a positive and a negative charge configuration, was investigated using a scanning tunneling microscope (STM) and noise analysis electronics. The dopant atom switching frequency shows a clear dependence on the bias voltage and tunneling current, because these parameters influence the escape and capture processes of electrons. Our physical model for these processes, taking into account the relevant tunneling barriers, matches well with the experimental data. By choosing the appropriate tunneling conditions, we show that a single dopant can be employed as a memory element. The STM tip serves both as an electrical gate to write and as a probe to read the information stored on a single Si atom.
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