Double-dot-like charge transport through a small size silicon single electron transistor

We report double dot like charge transport in a Si single electron transistor with a single fabricated dot. Detailed analysis of the transport data suggests the existence of another quantum dot with a size much larger than the fabricated dot. More importantly, it is shown that the Coulomb oscillations observed at high temperature clearly originate from the fabricated dot. Possible origin of the accidental formation of the second quantum dot is either a defect at the Si/buried oxide interface or a defect in the thermal oxide surrounding the Si quantum wire.