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Quantum dots-in-a-well infrared photodetectors for long wavelength infrared detection
Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
Synchrotron radiation research, Lund University, Box 118, S-22100 Lund, Sweden.
lndustrial Nano- and Microtechnology, Acreo AB, Electrum 236, S-16440 Kista, Sweden.
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2006 (English)In: Optical Materials in Defence Systems Technology III,2006, Proceedings of SPIE 6401: SPIE Digital Library , 2006, 640109- p.Conference paper, Published paper (Refereed)
Abstract [en]

We report on a quantum dots-in-a-well infrared photodetector (DWELL QDIP) grown by metal organic vapor phase epitaxy. The DWELL QDIP consisted of ten stacked InAs/In0.15Ga0.85As/GaAs QD layers embedded between n-doped contact layers. The density of the QDs was about 9 x 1010 cm-2 per QD layer. The energy level structure of the DWELL was revealed by optical measurements of interband transitions, and from a comparison with this energy level scheme the origin of the photocurrent peaks could be identified. The main intersubband transition contributing to the photocurrent was associated with the quantum dot ground state to the quantum well excited state transition. The performance of the DWELL QDIPs was evaluated regarding responsivity and dark current for temperatures between 15 K and 77 K. The photocurrent spectrum was dominated by a LWIR peak, with a peak wavelength at 8.4 μm and a full width at half maximum (FWHM) of 1.1 μm. At an operating temperature of 65 K, the peak responsivity was 30 mA/W at an applied bias of 4 V and the dark current was 1.2×10-5 A/cm2. Wavelength tuning from 8.4 μm to 9.5 μm was demonstrated, by reversing the bias of the detector.

Place, publisher, year, edition, pages
Proceedings of SPIE 6401: SPIE Digital Library , 2006. 640109- p.
National Category
Natural Sciences
Identifiers
URN: urn:nbn:se:liu:diva-36653DOI: 10.1117/12.690010Local ID: 32031OAI: oai:DiVA.org:liu-36653DiVA: diva2:257502
Available from: 2009-10-10 Created: 2009-10-10 Last updated: 2010-01-25Bibliographically approved
In thesis
1. InGaAs-based quantum dots for infrared imaging applications: growth and characterisation
Open this publication in new window or tab >>InGaAs-based quantum dots for infrared imaging applications: growth and characterisation
2007 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

In this thesis, results are presented from the development of quantum dot (QD) based infrared photodetectors (IPs). This includes epitaxial growth of QDs, investigations of the structural, optical and electronic properties of the QD based material as well as characterisation of the resulting components.

Metal organic vapour phase epitaxy is used for growth of selfassembled indium arsenide (lnAs) QDs on gallium arsenide (GaAs) substrates. Through characterisation by atomic force microscopy, the correlation between size distribution and density of quantum dots and different growth parameters, such as temperature, InAs deposition time and V/III-ratio (ratio between group Vand group III species) is achieved. The V/111ratio is identified as the most important parameter, in finding the right growth conditions for QDs. A route towards optimisation of the dot size distribution through successive variations of the growth parameters is presented.

The QD layers are inserted in Ino.15Gao.85As/GaAs quantum wells (QWs), forming so-called dots-in-a-well (DWELL) structures. These structures are used to fabricate IPs, primarily for detection in the long wavelength infrared region (LWIR, 8-12 µm).

The electron energy level schemes of the DWELL structures are deduced by means of Fourier transform photoluminescence (FTPL) and FTPL excitation (FTPLE) measurements. Further characterisation of the IPs, through interband and intersubband photocurrent (pe) measurements as weIl as dark current measurements, is performed. By comparisons of the deduced energy level scheme of the DWELL structure and the results of the intersubband PC measurements, the origin of the PC is determined. The main intersubband transition contributing to the PC is identified as the QD ground state to the QW excited state transition. Significant variations of PC and dark current are observed, when voltage and temperature are used as variable parameters. A possible explanation to this could be the strong variation of the escape probability from different energy states in the DWELL structure, as revealed by interband PC measurements. These results are important for the further optimisation of the DWELL lP.

Place, publisher, year, edition, pages
Kista Snabbtryck, 2007. 49 p.
Series
Linköping Studies in Science and Technology. Thesis, ISSN 0280-7971 ; 1297
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-52952 (URN)LIU-TEK-LIC-2007:6 (Local ID)978-91-85715-85-5 (ISBN)LIU-TEK-LIC-2007:6 (Archive number)LIU-TEK-LIC-2007:6 (OAI)
Presentation
(English)
Supervisors
Available from: 2010-01-25 Created: 2010-01-14 Last updated: 2010-01-25Bibliographically approved

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Höglund, LindaHoltz, Per-Olof

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