Displacement currents in semiconductor quantum dots embedded dielectric media: A method for room temperature photon detection

It is shown that the high electronic polarizability of quantum dots can be utilized to devise photon detectors by embedding quantum dots in dielectric media to form capacitors. Modulated light generates displacement currents and an expression is obtained for responsivity in terms of the properties of the quantum dot, the dielectric, and the detector geometry. A model detector constituted of PbS quantum dots embedded in paraffin wax is devised to illustrate the principle, giving similar to 0.6 A/W as an upper limit for the responsivity. As these systems sense only the variations of the light intensity, they could be operated at ambient temperature. (c) 2007 American Institute of Physics.