K. Kyuno

A conducting atomic force microscopy (C-AFM) in ultrahigh vacuum (UHV) is used to directly observe the evolution of leakage path in $\mathrm{Hf}{\mathrm{O}}_2∕\mathrm{Si}{\mathrm{O}}_2$ stacked gate dielectrics. Thanks to the UHV environment, reproducible results for both positive and negative tip biases are obtained without material formation on the surface, which has been a problem for atmospheric C-AFM. It is found that the density of leakage spots increases exponentially as a function of tip bias and that it is a large factor for leakage current increase.

The growth mechanism of pentacene thin films on a thermally grown $\mathrm{Si}{\mathrm{O}}_2$ on Si(100) substrate is examined in detail for a wide substrate temperature range $(223–342\mathrm{K})$ by analyzing the saturated island density and island size distribution. It is found that the log plot of the saturated island density as a function of inverse substrate temperature can be well represented by two straight lines and that these two regions have different critical cluster sizes for nucleation which is independently confirmed by island size distribution analysis. It is concluded that the nucleation behavior of pentacene thin films can be explained by the diffusion-mediated growth model well known in inorganic thin-film growth.