Dark current improvement by an in-situ plasma treatment on type-II superlattice LWIR photodetectors

Kang, Ko Ku; Ryu, Seong Min; Lee, Tae Hee; Kim, Jong Gi; Jang, Ahreum; Jeong, Hyun Chul; Eom, Jun Ho; Kim, Young Chul; Lee, Hyun Jin; Kim, Young Ho; Jung, Han; Kim, Sun Ho; Chi, Jong Hwa

doi:10.1117/12.2588041

Cited by 3 publications

(3 citation statements)

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“…Then, MWIR and LWIR bands are individually detected by a bias direction applied to the pixel electrode: negative (−) bias for MWIR and positive (+) bias for LWIR. The one-band nBn devices were fabricated through the steps of pixel isolation, posttreatment, passivation, and metallization processes [12][13][14][15][16]. However, the dual-band nBn device should be dry-etched more deeply than the one-band nBn device for pixel isolation because of the thicker absorber layer.…”

Section: Device Fabricationmentioning

confidence: 99%

“…3. First, LWIR absorber of each pixel was isolated by fully etching from the top contact layer to the barrier layer using inductively coupled plasma reactive ion etch (ICPRIE) under following conditions [15]: process temperature 200 °C, working pressure 6.66  10 −4 kPa, BCl3 flow 5 sccm, RF power 270 W, and ICP power 300 W. And then, to alleviate a potential surface damage of the etched LWIR absorber caused by plasma radicals, hydrogen (H2) plasma treatment was in situ performed using ICPRIE under following conditions [16,17]: process temperature 200°C, working pressure 6.66  10 −4 kPa, H2 flow 5 sccm, RF power 30 W, and ICP power 500 W. After SiO2 passivation film was deposited using an inductively coupled plasma chemical vapour deposition (ICPCVD) equipment to protect the surface of the LWIR absorber, the first MESA process for isolating the LWIR pixels was finished. Second, MWIR absorber of each pixel was isolated by fully etching from the barrier layer to the bottom contact layer under the same conditions as the pixel isolation process of the LWIR absorber.…”

Section: Device Fabricationmentioning

confidence: 99%

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Design and performance of dual-band MWIR/LWIR focal plane arrays based on a type-II superlattice nBn structure

2024

Opto-Electronics Review

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Dual-band infrared detector, which acquires more image information than single-band detectors, has excellent detection, recognition, and identification capabilities. The dual-band detector can have two bumps to connect with each absorber layer, but it is difficult to implement small pitch focal plane arrays and its fabrication process is complicated. Therefore, the most effective way for a dual-band detector is to acquire each band by biasselectable with one bump. To aim this, a dual-band MWIR/LWIR detector based on an InAs/GaSb type-II superlattice nBn structure was designed and its performance was evaluated in this work. Since two absorber layers were separated by the barrier layer, each band can be detected by bias-selectable with one bump. The fabricated dual-band device exhibited the dark current and spectral response characteristics of MWIR and LWIR bands under negative and positive bias, respectively. Spectral crosstalk that is a major issue in dualband detectors was also improved. Finally, a 20 m pitch 640  512 dual-band detector was fabricated, and both MWIR and LWIR images exhibited an average noise equivalent temperature difference of 30 mK or less at 80 K.

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Section: Device Fabricationmentioning

confidence: 99%

Section: Device Fabricationmentioning

confidence: 99%

Design and performance of dual-band MWIR/LWIR focal plane arrays based on a type-II superlattice nBn structure

2024

Opto-Electronics Review

View full text Add to dashboard Cite

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“…The MWIR absorber layer was grown earlier and thicker than LWIR absorber to minimize a spectral crossover when infrared is incident on the backside of the dual-band FPA [13]. The dual-band MWIR/LWIR FPA was fabricated following the process sequence of the InAs/GaSb LWIR nBn devices reported in previous studies [13,14,15,16,17]: dry-etch for pixel isolation, post-treament, passivation film deposition, electrode area etching, and metallization. However, the dual-band nBn device should be dry-etched more deeply than the single-band nBn device for pixel isolation because of the thicker absorber layer including MWIR and LWIR absorbers.…”

Section: Epi Structure and Device Fabricationmentioning

confidence: 99%

640 x 512 dual-band midwave and longwave infrared focal plane array at i3system

Lee

Eom

Kang

et al. 2023

Infrared Technology and Applications XLIX

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Each MWIR and LWIR detectror, which is widely used in various civil and military including chemical identification, atmospheric monitoring, guided weapon and surveillance reconnaissance systems, is advantageous for detecting hot and cool targets, respectively. Dual-band or multi-band detector that is able to detect more than two bands with only single detector has excellent recognition and identification capablities. Therefore, various groups have studied dual-band or multi-band detector since 1998. In this work, a 20 μm 640×512 dual-band midwave and longwave infrared detector with nBn structure was studied. A nBn detector is not only effective in reducing dark current, but it is relatively simple to implement a dual-band detector by growing MWIR and LWIR absorber layers on both sides of a barrier layer. The dual-band detector acquires each MWIR and LWIR bands by selecting the applied bias direction. Consequently, the 20 μm 640×512 dual-band MWIR/LWIR FPA hybridized to read-out integrated circuit (ROIC) exhibited that an average noise equivalent temperature difference (NETD) and operability of both MWIR and LWIR modes were less than 25 mK and more than 99.5 %, respectively.

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Quasi-3-dimensional simulations and experimental validation of surface leakage currents in high operating temperature type-II superlattice infrared detectors

Ramos

Delmas

Ivanov

et al. 2022

Journal of Applied Physics

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The surface leakage in InAs/GaSb type-II superlattice (T2SL) is studied experimentally and theoretically for photodiodes with small sizes down to 10 × 10 μm2. The dependence of dark current density on mesa size is studied at 110 and 200 K, and surface leakage is shown to impact both generation–recombination (GR) and diffusion dark current mechanisms. A quasi-3-dimensional model to simulate the fabrication process using surface traps on the pixel's sidewall is presented and is used to accurately represent the dark current of large and small pixels with surface leakage in the different temperature regimes. The simulations confirmed that the surface leakage current has a GR and diffusion component at low and high temperature, respectively. Finally, the surface leakage current has been correlated with the change in minority carrier concentration at the surface due to the presence of donor traps.

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Dark current improvement by an in-situ plasma treatment on type-II superlattice LWIR photodetectors

Cited by 3 publications

References 0 publications

Design and performance of dual-band MWIR/LWIR focal plane arrays based on a type-II superlattice nBn structure

Design and performance of dual-band MWIR/LWIR focal plane arrays based on a type-II superlattice nBn structure

640 x 512 dual-band midwave and longwave infrared focal plane array at i3system

Quasi-3-dimensional simulations and experimental validation of surface leakage currents in high operating temperature type-II superlattice infrared detectors

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