Qin, H. and Simmel, F. and Blick, R. H. and Kotthaus, J.P. and Wegscheider, Werner and Bichler, Max
Determination of the complex microwave photoconductance of a single quantum dot.
Physical Review B 63 (3), 035320.
A small quantum dot containing approximately 20 electrons is realized in a two-dimensional electron system of an AlxGa1-xAs/GaAs heterostructure. Conventional transport and microwave spectroscopy reveal the dot’s electronic structure. By applying a coherently coupled two-source technique, we are able to determine the complex microwave-induced tunnel current. The amplitude of this photoconductance resolves photon-assisted tunneling (PAT) in the nonlinear regime through the ground state and an excited state as well. The out-of-phase component (susceptance) allows us to study charge relaxation within the quantum dot on a time scale comparable to the microwave beat period.