InAs/GaSb quantum well structures of Infrared Detector applications. : Quantum well structure

The detection of MWIR (mid wavelength infrared radiation) is the important for industrial, biomedical and military applications.desirable for the radiation detector to operate in the middle wavelength IR (MWIR) band corresponding to a wavelength band ranging from about 3 microns to about 5 microns.Such MWIR detectors allow forobjects having a similar thermal signature. In addition, MWIR detectors may be used in low power applications such as in night vision for surveillance of personnel. Now a day commercially available uncooled IR sensors operating in MWIR region (2 – 5 μm) use microbolometric detectors which are inherently slow. The novel detector of InAs/GaSb quantum well structures overcomes this limitation. However, third-generation high-performance IR  FPAs are already an attractive proposition to the IR system designer. They covered such as multicolour (at least two, and maybe more different spectral bands) with the possibility of simultaneous detection in both space and time, and ever larger sizes of, say, 2000 × 2000, and operating at higher temperatures, even to room temperature, for all cut-off wavelengths.These hetero structures have a type-II band alignment such that the conduction band of InAs layer is lower than the valence band of GaSb layer. The effective bandgap of thesestructures can be adjusted from 0.4 eV to values below 0.1 eV by varying the thickness of constituent layers leading to an enormous range of detector cutoff wavelengths (3-20 This work is focused on the various key characteristics the optical (responsivity and detectivity) and electrical (surface leakage &amp; dark current) of infrared detector and proof of concept is demonstrated on infrared P-I-N photodiodes based on InAs/GaSb superlattices with ~8.5 μm cutoff wavelength and bandgap energy ~150 meV operating at 78 K where supression of surface leakage currents is observed. In certain military applications, it isthermal imaging of airplanes, artillery tanks and otherμm).Nice research work at Halmstad University</p

Type II GaSb/GaAs quantum dot/ring stacks with extended photoresponse for efficient solar cells

We report on the fabrication of GaAs based p-i-n solar cells containing 5 and 10 layers of type II GaSb quantum rings grown by molecular beam epitaxy. Solar cells containing quantum rings show improved efficiency at longer wavelengths into the near-IR extending up to 1500 nm and show enhanced short-circuit current under 1 sun illumination compared to a GaAs control cell. A reduction in the open-circuit voltage is observed due to the build-up of internal strain. The MBE growth, formation and photoluminescence of single and stacked layers of GaSb/GaAs quantum rings are also presented. (C) 2011 Elsevier B.V. All rights reserved

Rapid thermal annealing and photoluminescence of type-II GaSb single monolayer quantum dot stacks

The effects of rapid thermal annealing on the photoluminescence emission obtained from ten-layer stacks of GaSb/GaAs type-II single monolayer quantum dots and Stranski-Krastanow grown quantum rings have been studied and interpreted. Post-growth rapid thermal annealing was performed with proximity capping at temperatures from 550 degrees C to 800 degrees C, resulting in an increase in photoluminescence emission intensity and a blue shift in peak energy in both types of stacks, together with changes in the activation energy for thermal quenching. This behaviour originates from Sb-As intermixing and changes in morphology of the nanostructures formed using the two different growth mechanisms