Passivation of InAs∕(GaIn)Sb short-period superlattice photodiodes with 10μm cutoff wavelength by epitaxial overgrowth with AlxGa1−xAsySb1−y

Rehm, Robert; Walther, M.; Fuchs, F.; Schmitz, J.; Fleißner, J.

doi:10.1063/1.1906326

Cited by 119 publications

(65 citation statements)

References 10 publications

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“…The average external QE is seen to increase steadily with i-region thickness, up to a value of about 35% for the 4-µm-thick i-region device (measured within 25% of the cutoff wavelength), which is among the highest published for a type-II superlattice. 7,8 Transport properties were also measured, yielding average dynamic-impedance-area product (R 0 A) values of 10-20 Ohm-cm 2 at 80 K, which are comparable to the best previous type-II values, 9 but are about a factor of 10 lower than the state of the art for MCT in this wavelength range. In PIN photodiodes, the QE is largely determined by three factors: the absorption coefficient, the background impurity concentration in the i-region (N bgnd ), and the minority carrier diffusion length (L n ).…”

Section: Resultsmentioning

confidence: 86%

High quantum efficiency long-wave infrared photodiodes using W- structured type-II superlattices

et al. 2006

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Recent improvements in material quality and design have led to large improvements in the quantum efficiency (QE) of long-wave infrared (LWIR) photodiodes based on W-structured type-II superlattices (WSL), which now have achieved external QE of up to 35% on an 11.3 µm cutoff photodiode operating at 80K. While single band and dual band WSLs have been demonstrated with cutoff wavelengths out to 17 µm, the initial devices also showed significant losses of photo-excited carriers resulting in QE levels of ≤ 10%. Here we describe recent results in which these losses have been dramatically reduced by modifying the WSL barrier layers to increase the mini-band width and improve the material properties. An additional 35-55% increase in QE also resulted from the use of semitransparent Te doped n-GaSb substrates that allowed for IR reflections off the backside from the Au plated chip carrier. A series of PIN photodiodes using the improved WSL, with intrinsic regions from 1 to 4 µm thick, were used to study minority carrier transport characteristics in the new structure. As a result of the improved design and material properties, the electron diffusion length in the undoped i-region, as determined from a theoretical fit to the thickness-dependent data, was 3.5µm, allowing for much higher collection efficiency in PIN photodiodes with intrinsic regions up to 4 µm thick.

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Section: Resultsmentioning

confidence: 86%

High quantum efficiency long-wave infrared photodiodes using W- structured type-II superlattices

et al. 2006

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“…Especially for photodiodes in the 8-12 µm (LWIR) range sufficient reproducibility and long-term stability is difficult to achieve by the deposition of a dielectric passivation layer. Yet a promising method based on the epitaxial overgrowth of LWIR InAs/(GaIn)Sb short-period superlattice mesa devices with lattice matched Al x Ga 1-x As y Sb 1-y has been demonstrated recently [5]. The present paper focuses on the mid-IR (3-5 µm, MWIR) spectral range where the first fully operational 256´256 SL-camera was demonstrated last year [6].…”

Section: Introductionmentioning

confidence: 99%

InAs/GaSb superlattice focal plane arrays for high-resolution thermal imaging

Rehm

Walther

Schmitz

et al. 2006

Opto-Electronics Review

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The first fully operational mid-IR (3–5 μm) 256×256 IR-FPA camera system based on a type-II InAs/GaSb short-period superlattice showing an excellent noise equivalent temperature difference below 10 mK and a very uniform performance has been realized. We report on the development and fabrication of the detecor chip, i.e., epitaxy, processing technology and electro-optical characterization of fully integrated InAs/GaSb superlattice focal plane arrays. While the superlattice design employed for the first demonstrator camera yielded a quantum efficiency around 30%, a superlattice structure grown with a thicker active layer and an optimized V/III BEP ratio during growth of the InAs layers exhibits a significant increase in quantum efficiency. Quantitative responsivity measurements reveal a quantum efficiency of about 60% for InAs/GaSb superlattice focal plane arrays after implementing this design improvement.

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“…Especially for the FPA applications and long wavelength operations, passivation becomes a vital issue. In order to overcome surface leakage currents of small sized photodetectors, various passivation methods such sulfide [4,5], silicondioxide layers [6], polymeric layer [7] and even overgrowth with wide bandgap materials [8] were proposed. Passivation is expected to suppress oxidation of the side walls and saturate dangling bonds to prevent surface states.…”

Section: Introductionmentioning

confidence: 99%

Passivation of type II InAs/GaSb superlattice photodetectors with atomic layer deposited Al<sub>2</sub>O<sub>3</sub>

et al. 2012

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We have achieved significant improvement in the electrical performance of the InAs/GaSb midwave infrared photodetector (MWIR) by using atomic layer deposited (ALD) aluminium oxide (Al 2 O 3 ) as a passivation layer. Plasma free and low operation temperature with uniform coating of ALD technique leads to a conformal and defect free coverage on the side walls. This conformal coverage of rough surfaces also satisfies dangling bonds more efficiently while eliminating metal oxides in a self cleaning process of the Al 2 O 3 layer. Al 2 O 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 x 10 13 Jones, respectively at 4 µm and 77 K. Quantum efficiency (QE) was determined as %41 for these detectors.

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Passivation of InAs∕(GaIn)Sb short-period superlattice photodiodes with 10μm cutoff wavelength by epitaxial overgrowth with AlxGa1−xAsySb1−y

Cited by 119 publications

References 10 publications

High quantum efficiency long-wave infrared photodiodes using W- structured type-II superlattices

High quantum efficiency long-wave infrared photodiodes using W- structured type-II superlattices

InAs/GaSb superlattice focal plane arrays for high-resolution thermal imaging

Passivation of type II InAs/GaSb superlattice photodetectors with atomic layer deposited Al<sub>2</sub>O<sub>3</sub>

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Passivation of InAs∕(GaIn)Sb short-period superlattice photodiodes with 10μm cutoff wavelength by epitaxial overgrowth with AlxGa1−xAsySb1−y

Cited by 119 publications

References 10 publications

High quantum efficiency long-wave infrared photodiodes using W- structured type-II superlattices

High quantum efficiency long-wave infrared photodiodes using W- structured type-II superlattices

InAs/GaSb superlattice focal plane arrays for high-resolution thermal imaging

Passivation of type II InAs/GaSb superlattice photodetectors with atomic layer deposited Al&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt;

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Passivation of type II InAs/GaSb superlattice photodetectors with atomic layer deposited Al<sub>2</sub>O<sub>3</sub>