In this letter, we report an observation of room temperature electrical oscillation in vanadium dioxide (VO2), a representative strongly correlated material showing a metal-insulator transition. An electric circuit for the oscillation is simply composed of a voltage source and two-terminal VO2 thin film device serially connected with a standard resistor. The systematic procedures where the oscillation occurred were explained based on the electrical relationship between the VO2 device and resistor, and the generation window of the oscillation was determined. In particular, the oscillation frequency could be controlled by adjusting an external voltage and increased up to >0.5MHz.

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In atomic layer deposition ͑ALD͒, it is well known that a linear relationship exists between the deposited film thickness and the number of deposition cycles, which is due to its inherent characteristics of self-limited surface reaction between reactants. However, during the initial stage of ALD, the outermost surface is gradually converted from pre-deposited substrates into an actual film as ALD of the film proceeds. Therefore, a transient region should exist, which causes a nonlinear dependence of film thickness on the number of deposition cycles, because the characteristics of the surface adsorption of reactants is dependent on the exposed film surface. To estimate the accurate film thickness, especially for film thickness less than 10 nm, we propose a simple analytical kinetic model in the transient region. The experimental results of TiN-ALD performed on the SiO 2 substrate are consistent with the existence of the transient region. Furthermore, it has been found that the probability of adsorption of a reactant to predeposited SiO 2 is considerably lower than that to TiN films.

A kinetic model has been studied for exploring the prospects of atomic layer deposition (ALD) of TiN thin films. In the present article, assuming the existence for readsorption of each reactant, we can explain and model the film growth of 0–2 at. ML in one deposition cycle in TiN-ALD. Applying the proposed model to TiN films grown by ALD using tetrakis(dimethylamido)titanium and ammonia, the parameters related to both the adsorption rate and the adsorption order of each reactant were extracted. With the extracted parameters, TiN film thickness in one deposition cycle depending on the pulse time of each reactant could be predicted in a reasonable range of accuracy.