Capacitance Study of the Single Electron Addition Spectrum of Quantum Dot Arrays

Publisher Summary This chapter focuses on the effects of both single electron charging energy and quantum level splitting in a large array of small particles (quantum dots) coupled by tunneling to a metallic substrate. In a simple model, a single dot develops a spectrum of specific gate voltages at which electrons are energetically allowed to tunnel into and out of the dot. The Coulomb blockade and the quantum level structure of the dot regulate the entrance of electrons into a dot, allowing them to be added only one at a time, with spacings between the electronic additions at intervals in gate bias as large as 30 mV. The capacitance of these arrays to high resolution is presented as a function of gate bias and amplitude of measuring signal. Intriguing fluctuations, of amplitude on order 1 fF, are observed in the device capacitance. Some of these fluctuations consist of nearly periodic oscillations, which can persist for many cycles. This periodic structure reflects an almost regular spectrum of electron additions to the dots, with one oscillation occurring per electron addition to each of the dots in the array. Such oscillations are observed down to a mean occupancy of the dots by as few as 8 electrons.