Statistics of the Coulomb-blockade peak spacings of a silicon quantum dot

We present an experimental study of the fluctuations of Coulomb-blockade pe ak positions of a quantum dot. The dot is defined by patterning the two-dim ensional electron gas of a silicon metal-oxide-semiconductor field-effect t ransistor structure using stacked gates. This permits variation of the numb er of electrons on the quantum dot without significant shape distortion. Th e ratio of charging energy to single-particle energy is considerably larger than in comparable GaAs/AlxGa1-xAs quantum dots. The statistical distribut ion of the conductance peak spacings in the Coulomb-blockade regime was fou nd to be unimodal and does not follow the Wigner surmise. The fluctuations of the spacings are much larger than the typical single-particle level spac ing and thus clearly contradict the expectation of constant interaction-ran dom matrix theory. [S0163-1829(99)50916-8].