The paper presents the analysis of the performance of the InAs/InAsSb superlattice barrier detector operated at 230 K and long-wavelengths infrared spectrum (LWIR). To determine the position of the electron miniband and the first heavy hole state in the superlattice, we have used a k·p. Having the position of the conduction band and valence band we have to determine a correct band alignment between the barrier and absorber layer – the barrier in the valence band must be sufficiently low to ensure the flow of optically generated holes. We have considered an AlSb material for barrier best aligned to LWIR InAs/InAsSb superlattice absorber.
The paper presents the performance of the interband cascade type-II infrared InAs/GaSb superlattice photodetectors. Such photodetectors are made up of multiple stages, which are connected in series using an interband tunneling heterostructure. Each stage can be divided into three regions: absorber region, relaxation region and interband tunneling region. Cascade configurations allows to achieve fast response detectors. Making the assumption of bulk-like absorbers, we show how the standard semiconductor transport and recombination equations can be extended to the case of multiplestage devices. We report on the dependence of the Johnson-noise limited detectivity on the absorber thickness for a different number of stages. This allows optimization of the detector architecture, necessary to achieve high value of the detectivity. For this purpose, we make comparison of collection efficiency in single- and multiple-stage devices. The collection efficiency rapidly increases with increasing the number of stages in multiple-absorber detector, especially in situation where the absorber material’s diffusion length is less than absorption depth. We show that the optimal value of the detectivity for different number of stages does not change significantly. The potential benefits of the cascade architecture are shown to be higher in long-term detection regime.
In this paper interband cascade type-II InAs/GaSb superlattice photodetector in temperature range from 225 K to 300 K
is investigated. The article concerns the theoretical simulations of the detectivity characteristics of cascade detector with
equal absorber regions in each stage. The obtained theoretical characteristics are comparable to experimentally
measured, assuming that transport in absorber is determined by dynamics of intrinsic carriers. The greatest fit is observed
for overlap values which increase with decreasing temperature form 0.175 eV for 225 K to 0.132 eV for 300 K.
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