Coulomb blockade in a silicon-on-sapphire nanowire

The use of single electron devices as photon detectors, in the infrared wavelength range, is explored. The operating mechanism uses photon assisted tunneling so that the device current in a single electron transistor (SET) with a bias voltage of less than the Coulomb gap voltage depends on the fare of interaction with the photons. Coupling between the photons and the SET requires the use of a planar antenna structure so that the greatest response is from the substrate side. The use of an IR transparent substrate, such as sapphire, is important to maximise the detection sensitivity. The fabrication and electrical behaviour of SETs made using silicon-on-sapphire is described and the detection performance is predicted.