Probe and control of the reservoir density of states in single-electron devices

We present a systematic study of the density of states (DOS) in electron accumulation layers near a Si-SiO₂ interface. In the experiments we have employed two conceptually different objects to probe DOS, namely, a phosphorus donor and a quantum dot, both operating in the single-electron tunneling regime. We demonstrate how the peaks in reservoir DOS can be moved in the transport window independently of the other device properties. This method introduces a fast and convenient way of identifying excited states in these emerging nanostructures.