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Long-wavelength infrared photoluminescence from InGaSb/InAs quantum dots
KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
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2013 (English)In: Infrared physics & technology, ISSN 1350-4495, Vol. 59, 89-92 p.Article in journal (Refereed) Published
Abstract [en]

We study the growth of self-assembled InGaSb/InAs quantum dots (QDs) and investigate how gallium can be used to reduce the optical transition energy in the InSb QD system. InGaSb QDs were grown on InAs (0 0 1) substrates by metal-organic vapor-phase epitaxy (MOVPE) and the material was characterized by photoluminescence (PL) measurements. A PL peak wavelength is demonstrated beyond 8 μm at 77 K, which is significantly longer than what has been reported for InSb QDs. The results suggest that InGaSb QDs can be grown at a larger size than InSb QDs leading to reduced confinement in the QDs.

Place, publisher, year, edition, pages
2013. Vol. 59, 89-92 p.
Keyword [en]
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Other Physics Topics
URN: urn:nbn:se:kth:diva-122437DOI: 10.1016/j.infrared.2012.12.020ISI: 000320974800016ScopusID: 2-s2.0-84878345768OAI: diva2:622361

QC 20130816

Available from: 2013-05-21 Created: 2013-05-21 Last updated: 2013-08-16Bibliographically approved
In thesis
1. Type-II interband quantum dot photodetectors
Open this publication in new window or tab >>Type-II interband quantum dot photodetectors
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Photon detectors based on single-crystalline materials are of great interest for high performance imaging applications due to their low noise and fast response. The major detector materials for sensing in the long-wavelength infrared (LWIR) band (8-14 µm) are currently HgCdTe (MCT) and AlGaAs/GaAs quantum wells (QW) used in intraband-based quantum-well infrared photodetectors (QWIPs). These either suffer from compositional variations that are detrimental to the system performance as in the case of MCT, or, have an efficient dark current generation mechanism that limits the operating temperature as for QWIPs. The need for increased on-wafer uniformity and elevated operating temperatures has resulted in the development of various alternative approaches, such as type-II strained-layer superlattice detectors (SLSs) and intraband quantum-dot infrared photodetectors (QDIPs).

In this work, we mainly explore two self-assembled quantum-dot (QD) materials for use as the absorber material in photon detectors for the LWIR, with the aim to develop low-dark current devices that can allow for high operating temperatures and high manufacturability. The detection mechanism is here based on type-II interband transitions from bound hole states in the QDs to continuum states in the matrix material.

Metal-organic vapor-phase epitaxy (MOVPE) was used to fabricate (Al)GaAs(Sb)/InAs and In(Ga)Sb/InAs QD structures for the development of an LWIR active material. A successive analysis of (Al)GaAs(Sb) QDs using absorption spectroscopy shows strong absorption in the range 6-12 µm interpreted to originate in intra-valence band transitions. Moreover, record-long photoluminescence (PL) wavelength up to 12 µm is demonstrated in InSb- and InGaSb QDs.

Mesa-etched single-pixel photodiodes were fabricated in which photoresponse is demonstrated up to 8 µm at 230 K with 10 In0.5Ga0.5Sb QD layers as the active region. The photoresponse is observed to be strongly temperature-dependent which is explained by hole trapping in the QDs. In the current design, the photoresponse is thermally limited at typical LWIR sensor operating temperatures (60-120 K), which is detrimental to the imaging performance. This can potentially be resolved by selecting a matrix material with a smaller barrier for thermionic emission of photo-excited holes. If such an arrangement can be achieved, type-II interband InGaSb QD structures can turn out to be interesting as a high-operating-temperature sensor material for thermal imaging applications.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2013. 81 p.
Trita-ICT/MAP, 1653-7310Trita-ICT/MAP AVH, ISSN 1653-7610 ; 2013:03
photodetector, quantum dot, infrared, MOVPE, thermal imaging, type-II, photoluminescence, III/V, InSb, InGaSb, InAs
National Category
Nano Technology
Research subject
urn:nbn:se:kth:diva-122294 (URN)978-91-7501-779-2 (ISBN)
Public defence
2013-06-14, Room D, Isafjordsgatan 39, Kista, 10:00 (English)

QC 20130521

Available from: 2013-05-21 Created: 2013-05-17 Last updated: 2013-05-21Bibliographically approved

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Gustafsson, OscarBerggren, JesperHammar, Mattias
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