Oscillations of hopping conductance in an array of charge-tunable self-assembled quantum dots

An array of 3 x 10(7) Ge self-assembled quantum dots is embedded into the a ctive channel of a Si metal-oxide field-effect transistor. Conductance osci llations with the gate voltage resulting from successive loading of holes i nto the dots are observed. On the basis of measurements of the temperature dependence of the conductance maxima, the charge-transfer mechanism in the channel is identified as being due to variable-range hopping between the do ts, with the typical hopping energy determined by inter-dot Coulomb interac tion. The characteristic spatial dimension of the hole wavefunctions as wel l as the charging energies of the dots are determined from the conductance data.