The characteristic of elongated Coulomb-blockade regions in a Si quantum-dot device coupled via asymmetric tunnel barriers

We investigate the peculiar electrical characteristics of Si quantum-dot devices coupled with asymmetric source/drain tunnel barriers. When the thick and thin tunnel barriers connect the quantum-dot to the source and drain, respectively, an elongated Coulomb-blockade region is created and enables a precise, reliable, and systematic control of both Coulomb-blockade oscillation and negative-differential-conductance oscillation by means of bias voltages. The distinctive phenomenon is attributed to the renormalization of the electron charging energy requirements for the Coulomb blockade. In-depth analyses on the transport characteristics and transport mechanisms are discussed.