Hotspot mixing:A framework for heterodyne mixing in superconducting hot-electron bolometers

We propose a framework to interpret heterodyne mixing in superconducting hot-electron bolometers. The physical conversion process of the mixer is the result of an electronic hotspot, of which the length, and consequently the resistance, oscillates at the intermediate frequency. On the basis of this concept, we calculate the (un)pumped current–voltage relation, the dc voltage responsivity, and the mixer conversion efficiency

Indium contamination from the indium-tin-oxide electrode in polymer light-emitting diodes

We have found that polymer light-emitting diodes (LEDs) contain high concentrations of metal impurities prior to operation. Narrow peaks in the electroluminescence spectrum unambiguously demonstrate the presence of atomic indium and aluminum. Rutherford backscattering spectroscopy (RBS) and x-ray photoelectron spectroscopy (XPS) depth profiling data corroborate this result. An average indium concentration of 5 x 10(19)atoms/cm(3) originating from the indium-tin-oxide (ITO) electrode has been found in the polymer layer. (C) 1996 American Institute of Physics

Resistive transition of niobium superconducting hot-electron bolometer mixers

We present a model for the description of the resistive transition in hot-electron bolometer mixers. We show that the transition is a property of a superconducting microbridge connected to normal conducting cooling pads. Using the concepts of the superconducting proximity effect, charge-imbalance generation, and Andreev reflection, we have calculated the resistance versus temperature of the device and demonstrate its dependence on the length of the microbridge, both theoretically and experimentally. The analysis reopens the question of the relationship between the resistive transition and the situation in which the device is optimally operated as a heterodyne mixer