High-Temperature Coulomb Blockade

The Coulomb blockade effect is studied in a single-electron transistor – quantum dot, separated from source and drain areas by tunnel junctions. Peculiarity of the transistor is that it is made on the basis of semiconducting membrane, separated from the suffer. Separating the transistor from the suffer having high dielectric constant leads to the drastic decrease in the quantum dot capacity С and, therefore, to the increase in the Coulomb gap 2 e C/ . This value is important since it determines the upper limit of the transistor working temperature. A direct comparison of the Coulomb gaps before and after separating from the suffer shows that it increases from 40 K (in temperature units) for conventional transistor to 150 K for the «suspended» one. High value of the Coulomb gap has made it possible to observe clear diamond-like structure of condactance dependence on the gate and source-drain voltages, specific for the Coulomb blockade, while typical temperature of this kind of measurements on conventional single-electron transistors is about hundreds of millikelvins. An additional blockade effect, different from the conventional Coulomb blockade is observed. The nature of this effect can be connected with additional mechanical degrees of freedom of the transistor (elastic deformations).