Long-wavelength infrared quantum-dot based interband photodetectors
2011 (English)In: Infrared physics & technology, ISSN 1350-4495, Vol. 54, no 3, 287-291 p.Article in journal (Refereed) Published
We report on the design and fabrication of (Al)GaAs(Sb)/InAs tensile strained quantum-dot (QD) based detector material for thermal infrared imaging applications in the long-wavelength infrared (LWIR) regime. The detection is based on transitions between confined dot states and continuum states in a type-II band lineup, and we therefore refer to it as a dot-to-bulk (D2B) infrared photodetector with expected benefits including long carrier lifetime due to the type-II band alignment, suppressed Shockley-Read-Hall generation-recombination due to the relatively large-bandgap matrix material, inhibited Auger recombination processes due to the tensile strain and epitaxial simplicity. Metal-organic vapor-phase epitaxy was used to grow multiple (Al)GaAs(Sb) QD layers on InAs substrates at different QD nominal thicknesses, compositions, doping conditions and multilayer periods, and the material was characterized using atomic force and transmission electron microscopy, and Fourier-transform infrared absorption spectroscopy. Dot densities up to 1 x 10(11) cm(-2), 1 x 10(12) cm(-2) and 3 x 10(10) cm(-2) were measured for GaAs, AlGaAs and GaAsSb QDs, respectively. Strong absorption in GaAs, AlGaAs and GaAsSb multilayer QD samples was observed in the wavelength range 6-12 mu m. From the wavelength shift in the spectral absorption for samples with varying QD thickness and composition it is believed that the absorption is due to an intra- valance band transition. From this it is possible to estimate the type-II inter-band transition wavelength, thereby suggesting that (Al)GaAs(Sb) QD/InAs heterostructures are suitable candidates for LWIR detection and imaging.
Place, publisher, year, edition, pages
2011. Vol. 54, no 3, 287-291 p.
Photodetector, LWIR, QD, MOVPE
Electrical Engineering, Electronic Engineering, Information Engineering
IdentifiersURN: urn:nbn:se:kth:diva-34662DOI: 10.1016/j.infrared.2010.12.031ISI: 000290973200028ScopusID: 2-s2.0-79955029475OAI: oai:DiVA.org:kth-34662DiVA: diva2:425267
QC 20110621 Ingår i konferens: International Conference on the Quantum Structure Infrared Photodector (QSIP), Istanbul, TURKEY, AUG 15-20, 20102011-06-212011-06-132014-12-08Bibliographically approved