Charge detector realization for AlGaAs/GaAs quantum-dot cellular automata

We perform measurements on an AlGaAs/GaAs double-quantum-dot structure, where dots are separated by an opaque barrier and each dot conductance is measured independently and simultaneously. We measure the Coulomb blockade oscillations ~CBOs! for each dot when the structure is configured for one and two dots. When configured as a single-dot device, we sweep the backgate and observe different CBO periods for each dot measured independently, implying dots of different sizes. When the device is configured for two dots, we observe strongly modulated CBOs in the larger dot while CBOs in the smaller dot exhibit almost no influence due to the changing charge of the larger dot. From this experiment, we have realized a charge detection scheme where we observe strong coupling in the detector signal in addition to the detector exhibiting minimal effect on the dot being measured. For an implementation of quantum-dot cellular automata ~QCA!, ~1! cells must couple capacitively and ~2! one must be able to detect electron occupation of a quantum dot within a cell. With this investigation, we demonstrate these two key components required for QCA in AlGaAs/GaAs materials. © 1996 American Vacuum Society.