Browsing by Subject "Mid wave infrared (MWIR)"

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Open Access
Atomic layer deposited Al 2O 3 passivation of type II InAs/GaSb superlattice photodetectors
(AIP, 2012) Salihoğlu, Ömer; Muti, Abdullah; Kutluer, Kutlu; Tansel, T.; Turan, R.; Kocabaş, Coşkun; Aydınlı, Atilla
Taking advantage of the favorable Gibbs free energies, atomic layer deposited (ALD) aluminum oxide (Al 2O 3) was used as a novel approach for passivation of type II InAs/GaSb superlattice (SL) midwave infrared (MWIR) single pixel photodetectors in a self cleaning process (λ cut-off ∼ 5.1 m). Al 2O 3 passivated and unpassivated diodes were compared for their electrical and optical performances. For passivated diodes, the dark current density was improved by an order of magnitude at 77 K. The zero bias responsivity and detectivity was 1.33 A/W and 1.9 × 10 13 Jones, respectively at 4μm and 77 K. Quantum efficiency (QE) was determined as 41 for these detectors. This conformal passivation technique is promising for focal plane array (FPA) applications. © 2012 American Institute of Physics.
Open Access
High-efficiency low-crosstalk dielectric metasurfaces of mid-wave infrared focal plane arrays
(American Institute of Physics Inc., 2017) Akın, O.; Demir, Hilmi Volkan
High-resolution compact-size focal plane arrays (FPAs) suffer the fundamental geometrical tradeoff between the optical resolution (pixel size miniaturization) and the optical crosstalk (spillover of neighboring pixel focusing). For FPAs, our previously reported metallic metasurfaces reached an unprecedented level of crosstalk suppression. However, practical utilization of these metallic microlens arrays has proved to be intrinsically limited due to the low device efficiency (of the order of 0.10) resulting from the fundamental absorption losses of metals and their cross-polarization scheme. Exceeding this limit, here we show highly efficient microlens designs enabled by dielectric metasurfaces for mid-wave infrared (MWIR) operation. These dielectric MWIR FPAs allow for a substantially high device efficiency over 0.80 without compromising the optical crosstalk performance. Systematically studying dielectric nanoantennas of silicon nanodisks that do not dictate the cross-polarization scheme using full-wave solutions, we found that the optical crosstalk is suppressed to low levels ≤ 3.0% while sustaining the high efficiency. A figure-of-merit (FoM) defined for the device performance as the focusing efficiency per optical crosstalk times the f-number achieves 84, which is superior to all other types of MWIR FPAs reported to date, all falling below a maximum FoM of 70. These findings indicate that the proposed approach can pave the way for the practical usage of metasurface microlens arrays in MWIR.
Open Access
Low-frequency noise behavior at reverse bias region in InAs/GaSb superlattice photodiodes on mid-wave infrared
(SPIE, 2013) Tansel, T.; Kutluer, K.; Muti, Abdullah; Salihoğlu, Ömer; Aydınlı, Atilla; Turan, R.
We describe a relationship between the noise characterization and activation energy of InAs/GaSb superlattice Mid- Wavelength-Infrared photodiodes for different passivation materials applied to the device. The noise measurements exhibited a frequency dependent plateau (i.e. 1/f-noise characteristic) for unpassivated as well as Si3N4 passivated samples whereas 1/f-type low noise suppression (i.e. frequency independent plateau) with a noise current reduction of more than one order of magnitude was observed for SiO2 passivation. For reverse bias values below -0.15V, the classical Schottky-noise calculation alone did not appear to describe the noise mechanism in a SL noise behavior, which shows a divergence between theoretically and experimentally determined noise values. We identify that, the additional noise appears, with and without passivation, at the surface activation energy of < 60 meV and is inversely proportional to the reverse bias. This is believed to be caused by the surface dangling-bonds (as well as surface states) whose response is controlled by the applied reverse bias. The calculated noise characteristics showed a good agreement with the experimental data. © 2013 SPIE.