Mechanism of potential profile formation in silicon single-electron transistors fabricated using pattern-dependent oxidation

The origin of the potential profile in silicon single-electron transistors (SETs) fabricated using pattern-dependent oxidation (PADOX) is investigated by making use of the geometric structure measured by atomic force microsco pe (AFM), the bandgap reduction due to compressive stress generated during PADOX obtained using the first-principles calculation, and the effective po tential method. A probable mechanism for the formation of the potential pro file responsible for SET operation is proposed, The width reduction in the silicon wire region in the SET produces a tunnel barrier, while the compres sive stress lowers the bottom of the conduction band through the bandgap re duction and forms a potential well corresponding to an island in the tunnel barrier.