185 research outputs found
Quantum well infrared photodetectors hardiness to the non ideality of the energy band profile
We report results on the effect of a non-sharp and disordered potential in
Quantum Well Infrared Photodetectors (QWIP). Scanning electronic transmission
microscopy is used to measure the alloy profile of the structure which is shown
to present a gradient of composition along the growth axis. Those measurements
are used as inputs to quantify the effect on the detector performance (peak
wavelength, spectral broadening and dark current). The influence of the random
positioning of the doping is also studied. Finally we demonstrate that QWIP
properties are quite robust with regard to the non ideality of the energy band
profile
On conversion of luminescence into absorption and the van Roosbroeck-Shockley relation
The problem of conversion of experimentally measured luminescence spectrum
into the absorption cross section is revisited. The common practice of using
the van Roosbroeck-Shockley (or Kubo-Martin-Schwinger or Kennard-Stepanov)
relation in this context is incorrect because luminescence from semiconductors
is essentially all due to the spontaneous emission component of the
recombination of carriers distributed far-from-equilibrium. A simple,
physically consistent, and practical prescription for converting the
luminescence spectra into absorption is presented and its relation to the
so-called nonequilibrium generalization of the van Roosbroeck-Shockley
relationship is discussed.Comment: 3 pages, 2 figure
Patch antenna terahertz photodetectors
We report on the implementation of 5 THz quantum well photodetector exploiting a patch antenna cavity array. The benefit of our plasmonic architecture on the detector performance is assessed by comparing it with detectors made using the same quantum well absorbing region, but processed into a standard 45° polished facet mesa. Our results demonstrate a clear improvement in responsivity, polarization insensitivity, and background limited performance. Peak detectivities in excess of 5 × 1012 cmHz1/2/W have been obtained, a value comparable with that of the best cryogenic cooled bolometers
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