Quantum Dot Response in Different Regimes and its Applications

n this work the behavior of quantum dots is investigated in terms of temperature changes, the crossover from the tunneling regime to the open regime, and the frequency effects on a three-terminal channel where one side is blocked by a quantum dot. The device used here is a two-dimensional electron gas created within a GaAs/AlGaAs heterostructure. When energy levels of a quantum dot are coupled to the leads, electrons can tunnel through the quantum dot if the energy levels lie within the transport window. Temperature influences the Fermi distribution of the leads and as a result it changes the coupling of the energy levels to the leads. Once there exists a temperature difference between the leads, a thermocurrent can appear, even without applying any bias voltage to the system. Depending on the coupling of the energy levels to the leads, temperature can have different effects on each energy level. For understanding how electron transport through quantum dots is being affected different fitting functions are employed. For the second measurement, after creating a confined region where a quantum dot shows single-electron Coulomb blockade behavior, by changing the gate, its evolution to the open regime is investigated. Also, different coupling configurations are measured and analysed. A quantum point contact is used as a charge sensor for knowing the number of the electrons in the quantum dot. Depending on how the couplings work a quantum dot can exhibit Fabry-P´erot interference pattern when this crossover is taking place. Finally, in a three-terminal measurements, where for one side no restrictions are applied and the other side is blocked by a quantum dot. By applying frequency measurements to the system, it is investigated how both sides respond under such conditions. While the conductance on the quantum dot side increases, it decreases on the other side. Because of the capacitance coupling of the quantum dot and the kinetic inductance behavior of the two-dimensional electron gas, both sides show inverse response with respect to one another.