We fabricated a few electron vertical quantum dot (QD) device having four separate gate electrodesand characterized the electronic properties. In this device, geometrical symmetry in the confiningpotential for the QD, that is, orbital degeneracy for the QD electronic states can be tuned byadjusting the voltages applied to the four gates. It is then necessary to precisely characterize theperformance of each gate. We use a nonlinear single electron tunneling spectroscopy technique tocharacterize the gate performances and apply a capacitance network model for this device toreproduce the observed gate performances.
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