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Hsu, Chih-Wei
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Publications (10 of 23) Show all publications
Beshkova, M., Deminskyi, P., Hsu, C.-W., Shtepliuk, I., Avramova, I., Yakimova, R. & Pedersen, H. (2021). Atomic Layer Deposition of AlN on Graphene. Physica Status Solidi (a) applications and materials science, 218(17), Article ID 2000684.
Open this publication in new window or tab >>Atomic Layer Deposition of AlN on Graphene
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2021 (English)In: Physica Status Solidi (a) applications and materials science, ISSN 1862-6300, E-ISSN 1862-6319, Vol. 218, no 17, article id 2000684Article in journal (Refereed) Published
Abstract [en]

Graphene is a material with great promise for several applications within electronics. However, using graphene in any such application requires its integration in a stack of thin layers of materials. The ideal structure of graphene has a fully saturated surface without any binding sites for chemisorption of growth species, making film growth on graphene highly challenging. Herein, an attempt to deposit very thin layers of AlN using an atomic layer deposition approach is reported. It is demonstrated using X-ray photoelectron spectroscopy that Al-N are formed in the films deposited on graphene and shown by scanning electron microscopy and atomic force microscopy that the films have an island morphology. These results may be considered promising toward the development of a growth protocol for AlN on graphene and possibly also for 2D AlN fabrication.

Place, publisher, year, edition, pages
WILEY-V C H VERLAG GMBH, 2021
Keywords
SiC; AlN; atomic force microscopy; atomic layer deposition; graphene; scanning electron microscopy; X-ray photoelectron spectroscopy
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:liu:diva-180108 (URN)10.1002/pssa.202000684 (DOI)000665567100001 ()
Note

Funding Agencies|Bulgarian National Science FundNational Science Fund of Bulgaria [DN 18/6]; Swedish Foundation for Strategic Research through the project "Time-resolved low-temperature CVD for III-nitrides" [SSF-RMA 15-0018]; Knut and Alice Wallenberg Foundation through the project "Bridging the THz gap" [KAW 2013.0049]; Carl Trygger Foundation at the Linkoping University

Available from: 2021-10-08 Created: 2021-10-08 Last updated: 2022-09-05
Le, S. P., Hsu, C.-W., Martinovic, I. & Holtz, P.-O. (2021). GaN-based pyramidal quantum structures for micro-size light-emitting diode applications. Applied Physics Letters, 118(14), Article ID 142102.
Open this publication in new window or tab >>GaN-based pyramidal quantum structures for micro-size light-emitting diode applications
2021 (English)In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 118, no 14, article id 142102Article in journal (Refereed) Published
Abstract [en]

GaN-based pyramidal quantum structures, InGaN nanostructures located on top of micro-sized GaN pyramids, were fabricated by selective-area growth on SiC substrates by means of hot-wall metal-organic chemical vapor deposition. Arrays of GaN-based pyramidal structures exhibit micro-size pyramids possessing high uniformity, precise hexagonal bases, and InGaN/GaN quantum-well layers with well-defined interfaces. Each pyramid comprises a p-i-n InGaN/GaN structure, which is separated from that of other pyramids by a dielectric layer, serving as a building block for micro-emitters. Moreover, interconnected micro-size light-emitting diodes (microLEDs) built on the GaN-based pyramidal quantum structures were demonstrated, resulting in well-determined electroluminescence in the near-ultraviolet regime with negligible spectral shifts at high current levels. The results elucidated the rewards for development of these light-emitting designs and their potential for microLED applications.

Place, publisher, year, edition, pages
AMER INST PHYSICS, 2021
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:liu:diva-175431 (URN)10.1063/5.0048684 (DOI)000636948200002 ()
Note

Funding Agencies|Swedish Energy Agency, EELYS Program

Available from: 2021-05-04 Created: 2021-05-04 Last updated: 2023-05-16Bibliographically approved
Hsu, C.-W., Deminskyi, P., Persson, A., Karlsson, M. & Pedersen, H. (2021). On the dynamics in chemical vapor deposition of InN. Journal of Applied Physics, 130(13), Article ID 135302.
Open this publication in new window or tab >>On the dynamics in chemical vapor deposition of InN
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2021 (English)In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 130, no 13, article id 135302Article in journal (Refereed) Published
Abstract [en]

Epitaxial nanometer-thin indium nitride (InN) films are considered promising active layers in various device applications but remain challenging to deposit. We compare the morphological evolution and characterizations of InN films with various growth conditions in chemical vapor deposition (CVD) by both a plasma atomic layer deposition (ALD) approach and a conventional metalorganic CVD approach. Our results show that a time-resolved precursor supply is highly beneficial for deposition of smooth and continuous InN nanometer-thin films. The time for purging the reactor between the precursor pulses and low deposition temperature are key factors to achieve homogeneous InN. The gas exchange dynamics of the reactor is further studied using computational fluid dynamics. According to our study, 320 & DEG;C is found to be the upper temperature where the dynamics of the deposition chemistry can be controlled to involve only surface reactions with surface species. The results highlight the promising role of the ALD technique in realizing electronic devices based on nanometer-thin InN layers.

Place, publisher, year, edition, pages
AIP Publishing, 2021
National Category
Materials Chemistry
Identifiers
urn:nbn:se:liu:diva-180357 (URN)10.1063/5.0061926 (DOI)000703358200004 ()
Note

Funding Agencies|Swedish Foundation for Strategic Research through the project "Time-resolved low temperature CVD for III-nitrides" [SSF-RMA 15-0018]; Knut and Alice Wallenberg Foundation through the project "Bridging the THz gap" [KAW 2013.0049]; Carl Trygger Foundation; Swedish Research CouncilSwedish Research CouncilEuropean Commission [2018-05973]

Available from: 2021-10-18 Created: 2021-10-18 Last updated: 2022-09-05
Rouf, P., O´brien, N., Buttera, S. C., Martinovic, I., Bakhit, B., Martinsson, E., . . . Pedersen, H. (2020). Epitaxial GaN using Ga(NMe2)3 and NH3 plasma by Atomic Layer Deposition. Journal of Materials Chemistry C, 8(25), 8457-8465
Open this publication in new window or tab >>Epitaxial GaN using Ga(NMe2)3 and NH3 plasma by Atomic Layer Deposition
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2020 (English)In: Journal of Materials Chemistry C, ISSN 2050-7526, E-ISSN 2050-7534, Vol. 8, no 25, p. 8457-8465Article in journal (Refereed) Published
Abstract [en]

Low temperature deposition of high-quality epitaxial GaN is crucial for its integration in electronic applications. Chemical vapor deposition at approximately 800 °C using SiC with an AlN buffer layer or nitridized sapphire as substrate is used to facilitate the GaN growth. Here, we present a low temperature atomic layer deposition (ALD) process using tris(dimethylamido)gallium(III) with NH3 plasma. The ALD process shows self-limiting behaviour between 130–250 °C with a growth rate of 1.4 Å per cycle. The GaN films produced were crystalline on Si (100) at all deposition temperatures with a near stochiometric Ga/N ratio with low carbon and oxygen impurities. When GaN was deposited on 4H-SiC, the films grew epitaxially without the need for an AlN buffer layer, which has never been reported before. The bandgap of the GaN films was measured to be ∼3.42 eV and the Fermi level showed that the GaN was unintentionally n-type doped. This study shows the potential of ALD for GaN-based electronic devices.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2020
National Category
Materials Chemistry
Identifiers
urn:nbn:se:liu:diva-169938 (URN)10.1039/d0tc02085k (DOI)000545331300009 ()2-s2.0-85087704720 (Scopus ID)
Available from: 2020-09-25 Created: 2020-09-25 Last updated: 2022-09-05Bibliographically approved
Minamisawa, R. A., Mihaila, A., Farkas, I., Teodorescu, V. S., Afanasev, V. V., Chih-Wei, C.-W., . . . Rahimo, M. (2016). Characterization of a n+3C/n-4H SiC heterojunction diode. Applied Physics Letters, 108(14), 143502
Open this publication in new window or tab >>Characterization of a n+3C/n-4H SiC heterojunction diode
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2016 (English)In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 108, no 14, p. 143502-Article in journal (Refereed) Published
Abstract [en]

We report on the fabrication of n+3C/n-4H SiC heterojunction diodes (HJDs) potentially promising the ultimate thermal stability of the junction. The diodes were systematically analyzed by TEM, X-ray diffraction, AFM, and secondary ion mass spectroscopy, indicating the formation of epitaxial 3C-SiC crystal on top of 4H-SiC substrate with continuous interface, low surface roughness, and up to similar to 7 x 10(17) cm(-3) dopant impurity concentration. The conduction band off-set is about 1 V as extracted from CV measurements, while the valence bands of both SiC polytypes are aligned. The HJDs feature opening voltage of 1.65 V, consistent with the barrier height of about 1.5 eV extracted from CV measurement. We finally compare the electrical results of the n+3C/n-4H SiC heterojunction diodes with those featuring Si and Ge doped anodes in order to evaluate current challenges involved in the fabrication of such devices. (C) 2016 AIP Publishing LLC.

Place, publisher, year, edition, pages
American Institute of Physics (AIP), 2016
National Category
Chemical Sciences
Identifiers
urn:nbn:se:liu:diva-127776 (URN)10.1063/1.4945332 (DOI)000374230700040 ()
Available from: 2016-05-12 Created: 2016-05-12 Last updated: 2017-11-30
Chen, J.-T., Hsu, C.-W., Forsberg, U. & Janzén, E. (2015). Metalorganic chemical vapor deposition growth of high-mobility AlGaN/AlN/GaN heterostructures on GaN templates and native GaN substrates. Journal of Applied Physics, 117(8), Article ID 085301.
Open this publication in new window or tab >>Metalorganic chemical vapor deposition growth of high-mobility AlGaN/AlN/GaN heterostructures on GaN templates and native GaN substrates
2015 (English)In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 117, no 8, article id 085301Article in journal (Refereed) Published
Abstract [en]

Severe surface decomposition of semi-insulating (SI) GaN templates occurred in high-temperature H2 atmosphere prior to epitaxial growth in a metalorganic chemical vapor deposition system. A two-step heating process with a surface stabilization technique was developed to preserve the GaN template surface. Utilizing the optimized heating process, a high two-dimensional electron gas mobility ∼2000 cm2/V·s was obtained in a thin AlGaN/AlN/GaN heterostructure with an only 100-nm-thick GaN spacer layer homoepitaxially grown on the GaN template. This technique was also demonstrated viable for native GaN substrates to stabilize the surface facilitating two-dimensional growth of GaN layers. Very high residual silicon and oxygen concentrations were found up to ∼1 × 1020 cm−3 at the interface between the GaN epilayer and the native GaN substrate. Capacitance-voltage measurements confirmed that the residual carbon doping controlled by growth conditions of the GaN epilayer can be used to successfully compensate the donor-like impurities. State-of-the-art structural properties of a high-mobility AlGaN/AlN/GaN heterostructure was then realized on a 1 × 1 cm2 SI native GaN substrate; the full width at half maximum of the X-ray rocking curves of the GaN (002) and (102) peaks are only 21 and 14 arc sec, respectively. The surface morphology of the heterostructure shows uniform parallel bilayer steps, and no morphological defects were noticeable over the entire epi-wafer.

Place, publisher, year, edition, pages
American Institute of Physics (AIP), 2015
National Category
Physical Sciences
Identifiers
urn:nbn:se:liu:diva-117135 (URN)10.1063/1.4913223 (DOI)000351132500059 ()
Note

The authors would like to acknowledge the support from the Swedish Foundation for Strategic Research.

Available from: 2015-04-17 Created: 2015-04-17 Last updated: 2017-12-04Bibliographically approved
Chen, J.-T., Persson, I., Nilsson, D., Hsu, C.-W., Palisaitis, J., Forsberg, U., . . . Janzén, E. (2015). Room-Temperature mobility above 2200 cm2/V.s of two-dimensional electron gas in a sharp-interface AlGaN/GaN heterostructure. Applied Physics Letters, 106(25), Article ID 251601.
Open this publication in new window or tab >>Room-Temperature mobility above 2200 cm2/V.s of two-dimensional electron gas in a sharp-interface AlGaN/GaN heterostructure
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2015 (English)In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 106, no 25, article id 251601Article in journal (Refereed) Published
Abstract [en]

A high mobility of 2250 cm2/V·s of a two-dimensional electron gas (2DEG) in a metalorganic chemical vapor deposition-grown AlGaN/GaN heterostructure was demonstrated. The mobility enhancement was a result of better electron confinement due to a sharp AlGaN/GaN interface, as confirmed by scanning transmission electron microscopy analysis, not owing to the formation of a traditional thin AlN exclusion layer. Moreover, we found that the electron mobility in the sharp-interface heterostructures can sustain above 2000 cm2/V·s for a wide range of 2DEG densities. Finally, it is promising that the sharp-interface AlGaN/GaN heterostructure would enable low contact resistance fabrication, less impurity-related scattering, and trapping than the AlGaN/AlN/GaN heterostructure, as the high-impurity-contained AlN is removed.

Place, publisher, year, edition, pages
American Institute of Physics (AIP), 2015
National Category
Physical Sciences
Identifiers
urn:nbn:se:liu:diva-117133 (URN)10.1063/1.4922877 (DOI)000357036600005 ()
Available from: 2015-04-17 Created: 2015-04-17 Last updated: 2017-12-04Bibliographically approved
Lundskog, A., Hsu, C.-W., Karlsson, K. F., Amloy, S., Nilsson, D., Forsberg, U., . . . Janzén, E. (2014). Direct generation of linearly-polarized photon emission with designated orientations from site-controlled InGaN quantum dots. Light: Science & Applications, 3, Article ID e139.
Open this publication in new window or tab >>Direct generation of linearly-polarized photon emission with designated orientations from site-controlled InGaN quantum dots
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2014 (English)In: Light: Science & Applications, ISSN 2095-5545, Vol. 3, article id e139Article in journal (Refereed) Published
Abstract [en]

Semiconductor quantum dots (QDs) have been demonstrated viable for the emission of single photons on demand during the past decade. However, the synthesis of QDs emitting photons with pre-defined and deterministic polarization vectors has proven arduous. The access of linearly-polarized photons is essential for various applications. In this report, a novel concept to directly generate linearly-polarized photons is presented. This concept is based on InGaN QDs grown on top of elongated GaN hexagonal pyramids, by which predefined orientations herald the polarization vectors of the emitted photons from the QDs. This growth scheme should allow fabrication of ultracompact arrays of photon emitters, with a controlled polarization direction for each individual QD emitter.

Place, publisher, year, edition, pages
Nature Publishing Group, 2014
Keywords
GaN; InGaN; photoluminescence; polarized emission; quantum dot
National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-97417 (URN)10.1038/lsa.2014.20 (DOI)000331998400011 ()
Available from: 2013-09-12 Created: 2013-09-12 Last updated: 2017-04-11Bibliographically approved
Jemsson, T., Machhadani, H., Karlsson, F. K., Hsu, C.-W. & Holtz, P.-O. (2014). Linearly polarized single photon antibunching from a site-controlled InGaN quantum dot. Applied Physics Letters, 105(8), 081901-1-081901-4
Open this publication in new window or tab >>Linearly polarized single photon antibunching from a site-controlled InGaN quantum dot
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2014 (English)In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 105, no 8, p. 081901-1-081901-4Article in journal (Refereed) Published
Abstract [en]

We report on the observation of linearly polarized single photon antibunching in the excitonic emission from a site-controlled InGaN quantum dot. The measured second order coherence function exhibits a significant dip at zero time difference, corresponding to g(m)(2) (0) = 0: 90 under continuous laser excitation. This relatively high value of g(m)(2) (0) is well understood by a model as the combination of short exciton life time (320 ps), limited experimental timing resolution and the presence of an uncorrelated broadband background emission from the sample. Our result provides the first rigorous evidence of InGaN quantum dot formation on hexagonal GaN pyramids, and it highlights a great potential in these dots as fast polarized single photon emitters if the background emission can be eliminated.

Place, publisher, year, edition, pages
American Institute of Physics (AIP), 2014
National Category
Physical Sciences
Identifiers
urn:nbn:se:liu:diva-112065 (URN)10.1063/1.4893476 (DOI)000342753500022 ()
Note

Funding Agencies|Carl Trygger Foundation for Scientific Research; Swedish Research Council (VR); Nano-N consortium - Swedish Foundation for Strategic Research (SSF); Knut and Alice Wallenberg Foundation; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University (Faculty Grant SFO-Mat-LiU) [2009-00971]; Font-D, at Linkoping University

Available from: 2014-11-17 Created: 2014-11-13 Last updated: 2017-12-05Bibliographically approved
Lundskog, A., Hsu, C.-W., Nilsson, D., Karlsson, K. F., Forsberg, U., Holtz, P.-O. & Janzén, E. (2013). Controlled growth of hexagonal GaN pyramids by hot-wall MOCVD. Journal of Crystal Growth, 363, 287-293
Open this publication in new window or tab >>Controlled growth of hexagonal GaN pyramids by hot-wall MOCVD
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2013 (English)In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 363, p. 287-293Article in journal (Refereed) Published
Abstract [en]

Hexagonal GaN pyramids have been fabricated by hot-wall metal organic chemical vapor deposition (hot-wall MOCVD) and the growth evolution have been studied. It was concluded that the pyramid growth can be divided into two regimes separated by the adsorption kinetics of the {1101} surfaces of the pyramids. In the adsorption regime, the pyramids grow simultaneously in the <1101> and [0001] -directions. In the zero-adsorption regime the pyramids grow only in the [0001] direction. Thus the pyramid growth ceases when the (0001) facet growth has been terminated. Large arrays consisting of highly uniform pyramids with apex radii of 3 nm or less were achieved in the zeroadsorption regime. The growth-regime type was concluded to have a large impact on the uniformity degradation of the pyramids, and their optical properties. The impacts of threading dislocations which enter the pyramid from underneath are also discussed.

Keywords
A3. Hot wall epitaxy A3. Metalorganic vapor phase epitaxy A3. Selective epitaxy B1. Nitrides
National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-79317 (URN)10.1016/j.jcrysgro.2012.11.014 (DOI)000313205400047 ()
Available from: 2012-07-10 Created: 2012-07-10 Last updated: 2017-12-07Bibliographically approved
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