Electron transport in an array of platinum quantum dots

We fabricated an array of platinum quantum dots that are connected by amorphous carbon by electron beam induced deposition. The temperature dependent resistivity is studied. A crossover of the resistivity from the exp(T0/T)1/2 behavior to the activated behavior exp(T*/T) is observed at the critical temperature about 64 K. This crossover behavior is well described by the variation of Coulomb interaction depending on temperature, that is, the interaction with a soft Coulomb gap between the charged grains changes to the strong Coulomb blockade regime with the inelastic tunneling and small mean energy level spacing in a single grain