Thermal agglomeration of an ultrathin Si layer in silicon-on-insulator structures with a thickness ranging from 1 to 15 nm has been studied by atomic force microscopy. We found that the size of Si islands formed by agglomeration depends on the initial thickness of the Si layer, i.e., the height and the lateral size of Si islands increase with increasing Si thickness. Because the critical temperature for the agglomeration, however, is lower for thinner Si, the thickness dependence of Si island features is accompanied by a temperature effect. A calculation model based on both strain energy and surface free energy qualitatively explains most of the observed agglomeration phenomena, i.e., island formation and ordering.

Single-hole transport in a two-dimensional Si multidot-channel field-effect transistor is studied. It is found that the single-hole-tunneling current fluctuates in the particular ranges of drain voltage and gate voltage. Such a phenomenon can be explained by a model that the hole transport through the percolation path is sensitively influenced and fluctuates with the time due to charging–discharging and polarity-switching of the dots adjacent to the percolation path. A Monte Carlo simulation using a parallel-double-dot circuit shows good agreement with the experimental characteristics.