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Birch, Jens
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Publications (10 of 189) Show all publications
Li, Z., Sun, H., Hsiao, C.-L., Yao, Y., Xiao, Y., Shahi, M., . . . Zhang, F. (2018). A Free-Standing High-Output Power Density Thermoelectric Device Based on Structure-Ordered PEDOT:PSS. Advanced Electronic Materials, 4(2), Article ID 1700496.
Open this publication in new window or tab >>A Free-Standing High-Output Power Density Thermoelectric Device Based on Structure-Ordered PEDOT:PSS
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2018 (English)In: Advanced Electronic Materials, ISSN 2199-160X, Vol. 4, no 2, article id 1700496Article in journal (Refereed) Published
Abstract [en]

A free-standing high-output power density polymeric thermoelectric (TE) device is realized based on a highly conductive (approximate to 2500 S cm(-1)) structure-ordered poly(3,4-ethylenedioxythiophene):polystyrene sulfonate film (denoted as FS-PEDOT:PSS) with a Seebeck coefficient of 20.6 mu V K-1, an in-plane thermal conductivity of 0.64 W m(-1) K-1, and a peak power factor of 107 mu W K-2 m(-1) at room temperature. Under a small temperature gradient of 29 K, the TE device demonstrates a maximum output power density of 99 +/- 18.7 mu W cm(-2), which is the highest value achieved in pristine PEDOT:PSS based TE devices. In addition, a fivefold output power is demonstrated by series connecting five devices into a flexible thermoelectric module. The simplicity of assembling the films into flexible thermoelectric modules, the low out-of-plane thermal conductivity of 0.27 W m(-1) K-1, and free-standing feature indicates the potential to integrate the FS-PEDOT:PSS TE modules with textiles to power wearable electronics by harvesting human bodys heat. In addition to the high power factor, the high thermal stability of the FS-PEDOT:PSS films up to 250 degrees C is confirmed by in situ temperature-dependent X-ray diffraction and grazing incident wide angle X-ray scattering, which makes the FS-PEDOT:PSS films promising candidates for thermoelectric applications.

Place, publisher, year, edition, pages
Wiley-VCH Verlagsgesellschaft, 2018
Keywords
free-standing PEDOT:PSS film; output power density; p-type; thermoelectric generators
National Category
Other Materials Engineering
Identifiers
urn:nbn:se:liu:diva-145465 (URN)10.1002/aelm.201700496 (DOI)000424888600015 ()2-s2.0-85039784826 (Scopus ID)
Note

Funding Agencies|Vinnova Marie Curie incoming project [2016-04112]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University [200900971]; Recruitment Program of Global Youth Experts; National Natural Science Foundation of China [21474035]; United States National Science Foundation [DMR-1262261]; Open Fund of the State Key Laboratory of Luminescent Materials and Devices [2016-skllmd-03]; European Research Council [ERC 307596]

Available from: 2018-03-13 Created: 2018-03-13 Last updated: 2018-04-09Bibliographically approved
Junaid, M., Hsiao, C.-L., Chen, Y.-T., Lu, J., Palisaitis, J., Persson, P. O., . . . Birch, J. (2018). Effects of N2 Partial Pressure on Growth, Structure, and Optical Properties of GaN Nanorods Deposited by Liquid-Target Reactive Magnetron Sputter Epitaxy. Nanomaterials, 8(4), Article ID 223.
Open this publication in new window or tab >>Effects of N2 Partial Pressure on Growth, Structure, and Optical Properties of GaN Nanorods Deposited by Liquid-Target Reactive Magnetron Sputter Epitaxy
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2018 (English)In: Nanomaterials, ISSN 2079-4991, Vol. 8, no 4, article id 223Article in journal (Other academic) Published
Abstract [en]

GaN nanorods, essentially free from crystal defects and exhibiting very sharp band-edge luminescence, have been grown by reactive direct-current magnetron sputter epitaxy onto Si (111) substrates at a low working pressure of 5 mTorr. Upon diluting the reactive N2 working gas with a small amount of Ar (0.5 mTorr), we observed an increase in the nanorod aspect ratio from 8 to ~35, a decrease in the average diameter from 74 to 35 nm, and a two-fold increase in nanorod density. With further dilution (Ar = 2.5 mTorr), the aspect ratio decreased to 14, while the diameter increased to 60 nm and the nanorod density increased to a maximum of 2.4 × 109 cm−2. Yet, lower N2 partial pressures eventually led to the growth of continuous GaN films. The observed morphological dependence on N2 partial pressure is explained by a change from N-rich to Ga-rich growth conditions, combined with reduced GaN-poisoning of the Ga-target as the N2 gas pressure is reduced. Nanorods grown at 2.5 mTorr N2 partial pressure exhibited a high intensity 4 K photoluminescence neutral donor bound exciton transitions (D0XA) peak at ~3.479 eV with a full-width-at-half-maximum of 1.7 meV. High-resolution transmission electron microscopy corroborated the excellent crystalline quality of the nanorods.

Place, publisher, year, edition, pages
Basel, Switzerland: MDPI, 2018
Keywords
GaN, nanorods, X-ray diffraction, TEM, photoluminescence, magnetron sputter epitaxy, sputtering
National Category
Condensed Matter Physics Nano Technology
Identifiers
urn:nbn:se:liu:diva-84654 (URN)10.3390/nano8040223 (DOI)
Available from: 2018-04-09 Created: 2012-10-16 Last updated: 2018-04-24Bibliographically approved
Serban, E. A., Palisaitis, J., Persson, P. O., Hultman, L., Birch, J. & Hsiao, C.-L. (2018). Site-controlled growth of GaN nanorod arrays by magnetron sputter epitaxy. Thin Solid Films
Open this publication in new window or tab >>Site-controlled growth of GaN nanorod arrays by magnetron sputter epitaxy
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2018 (English)In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731Article in journal (Refereed) Epub ahead of print
Abstract [en]

Catalyst-free GaN nanorod regular arrays have been realized by reactive magnetron sputter epitaxy. Two nanolithographic methods, nanosphere lithography (NSL) and focused ion beam lithography (FIBL), were applied to pattern Si substrates with TiNx masks. The growth temperature was optimized for achieving selectivity and well-faceted nanorods grown onto the NSL-patterned substrates. With increasing temperature from 875 to 985 °C, we observe different growth behaviors and associate them with selective insensitive, diffusion-dominated, and desorption-dominated zones. To further achieve site-specific and diameter control, these growth parameters were transferred onto FIBL-patterned substrates. Further investigation into the FIBL process through tailoring of milling current and time in combination with varying nanorod growth temperature, suggests that minimization of mask and substrate damage is the key to attain uniform, well-defined, single, and straight nanorods. Destruction of the mask results in selective area growth failure, while damage of the substrate surface promotes inclined nanorods grown into the openings, owning to random oriented nucleation.

Place, publisher, year, edition, pages
Elsevier, 2018
Keywords
Gallium nitride, Magnetron sputter epitaxy, Selective-area growth, Nanorods, Lithography, Focused ion beam, Nanosphere
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:liu:diva-147648 (URN)10.1016/j.tsf.2018.01.050 (DOI)2-s2.0-85041572645 (Scopus ID)
Available from: 2018-05-03 Created: 2018-05-03 Last updated: 2018-06-18Bibliographically approved
Ghafoor, N., Eriksson, F., Andrew, A., Gullikson, E., Franz, S., Greczynski, G. & Birch, J. (2017). Impact of B4C co-sputtering on structure and optical performance of Cr/Sc multilayer X-ray mirrors. Optics Express, 25(15), 18274-18287
Open this publication in new window or tab >>Impact of B4C co-sputtering on structure and optical performance of Cr/Sc multilayer X-ray mirrors
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2017 (English)In: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 25, no 15, p. 18274-18287Article in journal (Refereed) Published
Abstract [en]

The influence of B4C incorporation during magnetron sputter deposition of Cr/Sc multilayers intended for soft X-ray reflective optics is investigated. Chemical analysis suggests formation of metal: boride and carbide bonds which stabilize an amorphous layer structure, resulting in smoother interfaces and an increased reflectivity. A near-normal incidence reflectivity of 11.7%, corresponding to a 67% increase, is achieved at λ = 3.11 nm upon adding 23 at.% (B + C). The advantage is significant for the multilayer periods larger than 1.8 nm, where amorphization results in smaller interface widths, for example, giving 36% reflectance and 99.89% degree of polarization near Brewster angle for a multilayer polarizer. The modulated ion-energy-assistance during the growth is considered vital to avoid intermixing during the interface formation even when B + C are added.

Place, publisher, year, edition, pages
Optical Society of America, 2017
National Category
Natural Sciences Inorganic Chemistry
Identifiers
urn:nbn:se:liu:diva-139944 (URN)10.1364/oe.25.018274 (DOI)000408584400128 ()28789315 (PubMedID)2-s2.0-85025823281 (Scopus ID)
Note

Funding agencies: Swedish Science Council; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University (Faculty Grant SFO-Mat-LiU) [2009 00971]

Available from: 2017-08-22 Created: 2017-08-22 Last updated: 2017-11-29Bibliographically approved
Serban, A., Palisaitis, J., Junaid, M., Tengdelius, L., Högberg, H., Hultman, L., . . . Hsiao, C.-L. (2017). Magnetron Sputter Epitaxy of High-Quality GaN Nanorods on Functional and Cost-Effective Templates/Substrates. Energies, 10(9), Article ID 1322.
Open this publication in new window or tab >>Magnetron Sputter Epitaxy of High-Quality GaN Nanorods on Functional and Cost-Effective Templates/Substrates
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2017 (English)In: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 10, no 9, article id 1322Article in journal (Refereed) Published
Abstract [en]

We demonstrate the versatility of magnetron sputter epitaxy by achieving high-quality GaN nanorods on different substrate/template combinations, specifically Si, SiC, TiN/Si, ZrB2/Si, ZrB2/SiC, Mo, and Ti. Growth temperature was optimized on Si, TiN/Si, and ZrB2/Si, resulting in increased nanorod aspect ratio with temperature. All nanorods exhibit high purity and quality, proved by the strong bandedge emission recorded with cathodoluminescence spectroscopy at room temperature as well as transmission electron microscopy. These substrates/templates are affordable compared to many conventional substrates, and the direct deposition onto them eliminates cumbersome post-processing steps in device fabrication. Thus, magnetron sputter epitaxy offers an attractive alternative for simple and affordable fabrication in optoelectronic device technology.

Place, publisher, year, edition, pages
Basel, Switzerland: MDPI AG, 2017
Keywords
GaN, nanorods, Si, SiC, Ti, Mo, TiN and ZrB2 templates, magnetron sputtering, epitaxy
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:liu:diva-141597 (URN)10.3390/en10091322 (DOI)000411225200078 ()2-s2.0-85029362447 (Scopus ID)
Note

Funding agencies: Swedish Research Council (VR) [621-2012-4420, 621-2013-5360, 2016-04412]; Swedish Governmental Agency for Innovation Systems (VINNOVA) under the VINNMER international qualification program; Swedish Foundation for Strategic Research (SSF) through the Resea

Available from: 2017-10-02 Created: 2017-10-02 Last updated: 2018-05-03Bibliographically approved
Tholander, C., Birch, J., Tasnádi, F., Hultman, L., Palisaitis, J., Persson, P. O., . . . Zukauskaitè, A. (2016). Ab initio calculations and experimental study of piezoelectric YxIn1-xN thin films deposited using reactive magnetron sputter epitaxy. Acta Materialia, 105, 199-206
Open this publication in new window or tab >>Ab initio calculations and experimental study of piezoelectric YxIn1-xN thin films deposited using reactive magnetron sputter epitaxy
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2016 (English)In: Acta Materialia, ISSN 1359-6454, E-ISSN 1873-2453, Vol. 105, p. 199-206Article in journal (Refereed) Published
Abstract [en]

By combining theoretical prediction and experimental verification we investigate the piezoelectric properties of yttrium indium nitride (YxIn1-xN). Ab initio calculations show that the YxIn1-xN wurtzite phase is lowest in energy among relevant alloy structures for 0≤x≤0.5. Reactive magnetron sputter epitaxy was used to prepare thin films with Y content up to x=0.51. The composition dependence of the lattice parameters observed in the grown films is in agreement with that predicted by the theoretical calculations confirming the possibility to synthesize a wurtzite solid solution. An AlN buffer layer greatly improves the crystalline quality and surface morphology of subsequently grown YxIn1-xN films. The piezoelectric response in films with x=0.09 and x=0.14 is observed using piezoresponse force microscopy. Theoretical calculations of the piezoelectric properties predict YxIn1−xN to have comparable piezoelectric properties to ScxAl1-xN.

Place, publisher, year, edition, pages
Elsevier, 2016
Keywords
YInN, Thin films, Sputter deposition, Piezoelectricity, Ab initio calculations
National Category
Condensed Matter Physics Materials Chemistry Inorganic Chemistry Other Materials Engineering Manufacturing, Surface and Joining Technology
Identifiers
urn:nbn:se:liu:diva-125918 (URN)10.1016/j.actamat.2015.11.050 (DOI)000370086500023 ()
Available from: 2016-03-08 Created: 2016-03-08 Last updated: 2017-11-30Bibliographically approved
Saha, B., Rui Koh, Y., Comparan, J., Sadasivam, S., Schroeder, J., Garbrecht, M., . . . Sands, T. D. (2016). Cross-plane thermal conductivity of (Ti,W)N/(Al,Sc)N metal/semiconductor superlattices. Physical Review B, 93(4), 045311
Open this publication in new window or tab >>Cross-plane thermal conductivity of (Ti,W)N/(Al,Sc)N metal/semiconductor superlattices
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2016 (English)In: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 93, no 4, p. 045311-Article in journal (Refereed) Published
Abstract [en]

Reduction of cross-plane thermal conductivity and understanding of the mechanisms of heat transport in nanostructured metal/semiconductor superlattices are crucial for their potential applications in thermoelectric and thermionic energy conversion devices, thermal management systems, and thermal barrier coatings. We have developed epitaxial (Ti,W)N/(Al,Sc)N metal/semiconductor superlattices with periodicity ranging from 1 nm to 240 nm that show significantly lower thermal conductivity compared to the parent TiN/(Al, Sc) N superlattice system. The (Ti,W)N/(Al,Sc)N superlattices grow with [001] orientation on the MgO(001) substrates with well-defined coherent layers and are nominally single crystalline with low densities of extended defects. Cross-plane thermal conductivity (measured by time-domain thermoreflectance) decreases with an increase in the superlattice interface density in a manner that is consistent with incoherent phonon boundary scattering. Thermal conductivity values saturate at 1.7W m(-1) K-1 for short superlattice periods possibly due to a delicate balance between long-wavelength coherent phonon modes and incoherent phonon scattering from heavy tungsten atomic sites and superlattice interfaces. First-principles density functional perturbation theory based calculations are performed to model the vibrational spectrum of the individual component materials, and transport models are used to explain the interface thermal conductance across the (Ti,W)N/(Al,Sc)N interfaces as a function of periodicity. The long-wavelength coherent phonon modes are expected to play a dominant role in the thermal transport properties of the short-period superlattices. Our analysis of the thermal transport properties of (Ti,W)N/(Al,Sc)N metal/semiconductor superlattices addresses fundamental questions about heat transport in multilayer materials.

Place, publisher, year, edition, pages
AMER PHYSICAL SOC, 2016
National Category
Physical Sciences
Identifiers
urn:nbn:se:liu:diva-125146 (URN)10.1103/PhysRevB.93.045311 (DOI)000368487500010 ()
Note

Funding Agencies|National Science Foundation; U.S. Department of Energy [CBET-1048616]; Defense Advanced Research Projects Agency (DARPA)/Army Research Office [W911NF0810347]; Louis Stokes Alliance for Minority Participation (LSAMP) program; Office of Naval Research [N000141211006]; Swedish Research Council [RAC Frame Program] [2011-6505]; Swedish Research Council [Linnaeus Grant (LiLi-NFM)]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University [SFO-Mat-LiU 2009-00971]

Available from: 2016-02-15 Created: 2016-02-15 Last updated: 2017-11-30
Chen, Y.-T., Karlsson, K. F., Birch, J. & Holtz, P.-O. (2016). Determination of critical diameters for intrinsic carrier diffusion-length of GaN nanorods with cryo-scanning near-field optical microscopy. Scientific Reports, 6(21482), 1-7
Open this publication in new window or tab >>Determination of critical diameters for intrinsic carrier diffusion-length of GaN nanorods with cryo-scanning near-field optical microscopy
2016 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 6, no 21482, p. 1-7Article in journal (Refereed) Published
Abstract [en]

Direct measurements of carrier diffusion in GaN nanorods with a designed InGaN/GaN layer-in-a-wire structure by scanning near-field optical microscopy (SNOM) were performed at liquid-helium temperatures of 10 K. Without an applied voltage, intrinsic diffusion lengths of photo-excited carriers were measured as the diameters of the nanorods differ from 50 to 800 nm. The critical diameter of nanorods for carrier diffusion is concluded as 170 nm with a statistical approach. Photoluminescence spectra were acquired for different positions of the SNOM tip on the nanorod, corresponding to the origins of the well-defined luminescence peaks, each being related to recombination-centers. The phenomenon originated from surface oxide by direct comparison of two nanorods with similar diameters in a single map has been observed and investigated.

Place, publisher, year, edition, pages
NATURE PUBLISHING GROUP, 2016
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:liu:diva-125803 (URN)10.1038/srep21482 (DOI)000370040800001 ()26876009 (PubMedID)
Note

Funding Agencies|Knut and Alice Wallenberg Foundation

Available from: 2016-03-08 Created: 2016-03-04 Last updated: 2017-11-30
Ektarawong, A., Simak, S., Hultman, L., Birch, J., Tasnádi, F., Wang, F. & Alling, B. (2016). Effects of configurational disorder on the elastic properties of icosahedral boron-rich alloys based on B6O, B13C2, and B4C, and their mixing thermodynamics. Journal of Chemical Physics, 144(13), Article ID 134503.
Open this publication in new window or tab >>Effects of configurational disorder on the elastic properties of icosahedral boron-rich alloys based on B6O, B13C2, and B4C, and their mixing thermodynamics
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2016 (English)In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 144, no 13, article id 134503Article in journal (Refereed) Published
Abstract [en]

The elastic properties of alloys between boron suboxide (B6O) and boron carbide (B13C2), denoted by (B6O)1−x(B13C2)x, as well as boron carbide with variable carbon content, ranging from B13C2 to B4C are calculated from first-principles. Furthermore, the mixing thermodynamics of (B6O)1−x(B13C2)x is studied. A superatom-special quasirandom structure approach is used for modeling different atomic configurations, in which effects of configurational disorder between the carbide and suboxide structural units, as well as between boron and carbon atoms within the units, are taken into account. Elastic properties calculations demonstrate that configurational  disorder in B13C2, where a part of the C atoms in the CBC chains substitute for B atoms in the B12 icosahedra, drastically increase the Young’s and shear modulus, as compared to an atomically ordered state, B12(CBC). These calculated elastic moduli of the disordered state are in excellent agreement with experiments. Configurational disorder between boron and carbon can also explain the experimentally observed almost constant elastic moduli of boron carbide as the carbon content is changed from B4C to B13C2. The elastic moduli of the (B6O)1−x(B13C2)x system are also practically unchanged with composition if boron-carbon disorder is taken into account. By investigating the mixing thermodynamics of the alloys, in which the Gibbs free energy is determined within the mean-field approximation for the configurational entropy, we outline the pseudo-binary phase diagram of (B6O)1−x(B13C2)x. The phase diagram reveals the existence of a miscibility gap at all temperatures up to the melting point. Also, the coexistence of B6O-rich as well as ordered or disordered B13C2-rich domains in the material prepared through equilibrium routes is predicted.

Place, publisher, year, edition, pages
American Institute of Physics (AIP), 2016
National Category
Physical Sciences
Identifiers
urn:nbn:se:liu:diva-122425 (URN)10.1063/1.4944982 (DOI)000374527900023 ()27059576 (PubMedID)
Note

Funding agencies:Swedish Research Council (VR) [621-2011-4417, 330-2014-6336, 2011-42-59]; CeNano at Linkoping University; Ministry of Education and Science of the Russian Federation in the framework of Increase Competitiveness Program of NUST "MISiS" [K3-2014-049]; LiLi-

At the time for thesis presentation publication was in status: Manuscript

Available from: 2015-11-02 Created: 2015-11-02 Last updated: 2017-12-01Bibliographically approved
Pfeiffer, D., Resnati, F., Birch, J., Etxegarai, M., Hall-Wilton, R., Höglund, C., . . . Thuiner, P. (2016). First measurements with new high-resolution gadolinium-GEM neutron detectors. Journal of Instrumentation, 11(P05011)
Open this publication in new window or tab >>First measurements with new high-resolution gadolinium-GEM neutron detectors
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2016 (English)In: Journal of Instrumentation, ISSN 1748-0221, E-ISSN 1748-0221, Vol. 11, no P05011Article in journal (Refereed) Published
Abstract [en]

European Spallation Source instruments like the macromolecular diffractometer (NMX) require an excellent neutron detection efficiency, high-rate capabilities, time resolution, and an unprecedented spatial resolution in the order of a few hundred micrometers over a wide angular range of the incoming neutrons. For these instruments solid converters in combination with Micro Pattern Gaseous Detectors (MPGDs) are a promising option. A GEM detector with gadolinium converter was tested on a cold neutron beam at the IFE research reactor in Norway. The mu TPC analysis, proven to improve the spatial resolution in the case of B-10 converters, is extended to gadolinium based detectors. For the first time, a Gd-GEM was successfully operated to detect neutrons with a measured efficiency of 11.8% at a wavelength of 2 angstrom and a position resolution better than 250 mu m.

Place, publisher, year, edition, pages
IOP PUBLISHING LTD, 2016
Keywords
Neutron detectors (cold, thermal, fast neutrons); Neutron diffraction detectors; Particle tracking detectors
National Category
Accelerator Physics and Instrumentation
Identifiers
urn:nbn:se:liu:diva-130142 (URN)10.1088/1748-0221/11/05/P05011 (DOI)000377851700034 ()
Note

Funding Agencies|EU Horizon 2020 framework, BrightnESS project [676548]

Available from: 2016-07-12 Created: 2016-07-11 Last updated: 2017-11-28
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