liu.seSearch for publications in DiVA
Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
A Study of Group 13-Nitride Atomic Layer Deposition: Computational Chemistry Modelling of Atomistic Deposition Processes
Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, Faculty of Science & Engineering.
2023 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The crystalline solids aluminium nitride (AlN), gallium nitride (GaN) and indium nitride (InN), together with their alloys, are of huge interest in the semiconductor industry. Their bandgaps span an extensive range from 6.0 eV for AlN to 0.7 eV for InN, with GaN in between at a bandgap of 3.6 eV. Thus, with bandgap tuning from infrared (IR) to ultraviolet (UV) they are well suited for photoelectric applications such as light emitting diodes (LED). The higher bandgaps of AlN and GaN compared to that of silicon (1.1 eV) makes them suitable for high power applications while the high electron mobility of InN makes it attractive for high frequency transistors. Since aluminium, gallium, and indium belong to group 13, their nitrides are termed group 13-nitrides (13Ns).  

The deposition techniques chemical vapor deposition (CVD) and atomic layer deposition (ALD) can be used to produce thin films upon a substrate through reactions by suitable precursor molecules in the gas phase or at the surface. These techniques have successfully deposited thin films of 13Ns using commercially available precursors, e.g., trimethyl aluminium (TMA), trimethyl gallium (TMG) and trimethyl indium (TMI) as metal precursor and ammonia (NH3) as nitrogen precursor. However, the chemistry between these precursors is not well developed, as evidenced by the large nonstoichiometric ratio between the metal and nitrogen precursors, in the order of 1:100-1:105. This is not sustainable for mass production of these materials, as significant amounts of precursor gas are wasted and must either be cleaned from the exhaust or be released into the atmosphere. In my thesis, the gas phase decomposition and the surface adsorption of these precursors and alternatives are investigated by computational approaches.  

Gas phase decomposition of ammonia is investigated by kinetic modelling at relevant temperature and pressures. At these conditions, a very small fraction of the initial ammonia molecules can decompose within the expected residence time for the gases in the process. The conclusion is that the low reactivity of ammonia is intrinsic and is not due to decomposition into unreactive nitrogen and hydrogen gas. Methylamines as alternative nitrogen precursors are explored for CVD of GaN. Although these are more reactive in the gas phase, their lower surface reactivity compared to ammonia limits their use as a replacement for ammonia in 13N CVD. The origin of the surface reactivity of ammonia in thermal ALD of AlN and GaN, in comparison to the lack of reactivity on InN, is explored. Comparing GaN and InN surface chemistry, the surface adsorption process on InN is less favourable than on GaN as well as being many orders of magnitude slower, indicating that the lack of any reported thermal ALD process on InN arises from the low reactivity of ammonia towards the InN surface.  

The resulting surface terminations after ammonia dosing determines how the metal precursors adsorb and react. A series of nitrogen rich surface terminations of the 13Ns is investigated by density functional theory (DFT) modelling and their stability and prevalence at different temperature and pressures are determined from statistical thermodynamics. At low temperatures the surfaces are terminated by hydrogen bonding amino groups while at high temperatures the surface is bare, with the transition temperature between the two structures decreasing from AlN to GaN to InN. TMA can adsorb onto the amino terminated surface and loses ligands by decomposing. Subsequent TMA molecules are found to decompose in two ways depending on how close it adsorbed to an already adsorbed and decomposed molecule.  

A suitable alternative class of metal precursor for 13N ALD are molecules with nitrogen to metal bonds, such as formamidinates, amidinates, trisguanidinates, or triazenides. Ammonia will have an easier process to break the weaker metal nitrogen bond compared to a metal carbon bond. The gas phase decomposition of a trisguanidinate precursor is investigated but it is shown to be likely to decompose during volatilization, limiting its use as an InN ALD precursor.  

My thesis consists of detailed atomistic simulations of the deposition of AlN, GaN and InN thin films. The simulations in cooperation with experimental work are used to elucidate the detailed atomistic mechanisms occurring during the process. It gives insight into the shortcomings of the current processes and precursors and can be used as a basis for how to improve them, rendering the 13N a suitable material in a sustainable large-scale production for a variety of semiconductor applications. 

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2023. , p. 73
Series
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 2295
National Category
Materials Chemistry
Identifiers
URN: urn:nbn:se:liu:diva-191935DOI: 10.3384/9789180750738ISBN: 9789180750721 (print)ISBN: 9789180750738 (electronic)OAI: oai:DiVA.org:liu-191935DiVA, id: diva2:1739320
Public defence
2023-03-29, Planck, F-building, Campus Valla, Linköping, 09:15 (English)
Opponent
Supervisors
Available from: 2023-02-24 Created: 2023-02-24 Last updated: 2023-02-27Bibliographically approved
List of papers
1. Kinetic modeling of ammonia decomposition at chemical vapor deposition conditions
Open this publication in new window or tab >>Kinetic modeling of ammonia decomposition at chemical vapor deposition conditions
2020 (English)In: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 38, no 5, article id 050402Article in journal (Refereed) Published
Abstract [en]

Kinetic modeling has been used to study the decomposition chemistry of ammonia at a wide range of temperatures, pressures, concentrations, and carrier gases mimicking the conditions in chemical vapor deposition (CVD) of metal nitrides. The modeling shows that only a small fraction of the ammonia molecules will decompose at most conditions studied. This suggests that the fact that the high NH3 to metal ratios often employed in CVD is due to the very low amount of reactive decomposition products being formed rather than due to rapid decomposition of ammonia into stable dinitrogen and dihydrogen as suggested by purely thermodynamic equilibrium models.

Place, publisher, year, edition, pages
A V S AMER INST PHYSICS, 2020
National Category
Inorganic Chemistry
Identifiers
urn:nbn:se:liu:diva-169219 (URN)10.1116/6.0000369 (DOI)000561391400001 ()
Note

Funding Agencies|Swedish foundation for Strategic Research through the project "Time-resolved low temperature CVD for III-nitrides" [SSF-RMA 15-0018]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at the Linkoping University (Faculty Grant SFO Mat LiU) [2009 00971]; Swedish Research Council (VR)Swedish Research Council

Available from: 2020-09-12 Created: 2020-09-12 Last updated: 2023-02-24
2. Methylamines as Nitrogen Precursors in Chemical Vapor Deposition of Gallium Nitride
Open this publication in new window or tab >>Methylamines as Nitrogen Precursors in Chemical Vapor Deposition of Gallium Nitride
Show others...
2019 (English)In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 123, no 11, p. 6701-6710Article in journal (Refereed) Published
Abstract [en]

Chemical vapor deposition (CVD) is one of the most important techniques for depositing thin films of the group 13 nitrides (13-Ns), AIN, GaN, InN, and their alloys, for electronic device applications. The standard CVD chemistry for 13-Ns uses ammonia as the nitrogen precursor; however, this gives an inefficient CVD chemistry, forcing N/13 ratios of 100/1 or more. Here, we investigate the hypothesis that replacing the N-H bonds in ammonia with weaker N-C bonds in methylamines will permit better CVD chemistry, allowing lower CVD temperatures and an improved N/13 ratio. Quantum chemical computations show that while the methylamines have a more reactive gas-phase chemistry, ammonia has a more reactive surface chemistry. CVD experiments using methylamines failed to deposit a continuous film, while instead micrometer-sized gallium droplets were deposited. This study shows that the nitrogen surface chemistry is most likely more important to be considered than the gas-phase chemistry when searching for better nitrogen precursors for 13-N CVD.

Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2019
National Category
Inorganic Chemistry
Identifiers
urn:nbn:se:liu:diva-156198 (URN)10.1021/acs.jpcc.9b00482 (DOI)000462260700044 ()
Note

Funding Agencies|Swedish foundation for Strategic Research [SSF-RMA 15-0018]; Vinnova VINNMER Marie Curie incoming mobility program [2015-03714]; COST (European Cooperation in Science and Technology) [MP1402]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University (Faculty Grant SFO Mat LiU) [2009 00971]

Available from: 2019-04-09 Created: 2019-04-09 Last updated: 2023-02-24
3. On the limitations of thermal atomic layer deposition of InN using ammonia
Open this publication in new window or tab >>On the limitations of thermal atomic layer deposition of InN using ammonia
2023 (English)In: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 41, no 2, article id 020401Article in journal (Refereed) Published
Abstract [en]

Chemical vapor deposition of indium nitride (InN) is severely limited by the low thermal stability of the material, and, thus, low-temperature deposition processes such as atomic layer deposition (ALD) are needed to deposit InN films. The two chemically and structurally closely related materials—aluminum nitride and gallium nitride (GaN)—can be deposited by both plasma and thermal ALD, with ammonia (NH3) as a nitrogen precursor in thermal processes. InN, however, can only be deposited using plasma ALD, indicating that there might be a limitation to thermal ALD with NH3 for InN. We use quantum-chemical density functional theory calculations to compare the adsorption process of NH3 on GaN and InN to investigate if differences in the process could account for the lack of thermal ALD of InN. Our findings show a similar reactive adsorption mechanism on both materials, in which NH3 could adsorb onto a vacant site left by a desorbing methyl group from the surfaces. The difference in energy barrier for this adsorption indicates that the process is many magnitudes slower on InN compared to GaN. Slow kinetics would hinder NH3 from reactively adsorbing onto InN in the timeframe of the ALD growth process and, thus, limit the availability of a thermal ALD process.

Place, publisher, year, edition, pages
American Vacuum Society, 2023
National Category
Materials Chemistry
Identifiers
urn:nbn:se:liu:diva-191934 (URN)10.1116/6.0002355 (DOI)000936907900001 ()
Note

Funding agencies: This project was funded by the Swedish Foundation for Strategic Research through the project “Time-resolved low temperature CVD for III-nitrides” (No. SSF-RMA 15-0018). L.O. acknowledges financial support from the Swedish Research Council (VR). Supercomputing resources were provided by the Swedish National Infrastructure for Computing (SNIC) and the Swedish National Supercomputer Centre (NSC).

Available from: 2023-02-24 Created: 2023-02-24 Last updated: 2023-03-21Bibliographically approved
4. Surface Structures from NH(3) Chemisorption in CVD and ALD of AlN, GaN, and InN Films
Open this publication in new window or tab >>Surface Structures from NH(3) Chemisorption in CVD and ALD of AlN, GaN, and InN Films
2022 (English)In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 126, no 13, p. 5885-5895Article in journal (Refereed) Published
Abstract [en]

Aluminum nitride (AlN), gallium nitride (GaN),and indium nitride (InN) form a family of technologicallyimportant semiconductors of high importance to light-emittingdiodes and high-frequency electronics. Although thinfilms of thesematerials are routinely manufactured by chemical vapor deposition(CVD) and atomic layer deposition (ALD), these methods are farfrom optimal and knowledge of the underlying chemical processesis lacking. In this work, we performed ab initio investigations of thesurface coverage of these materials under an ammonia-richatmosphere. Periodic density functional theory calculations wereused to test the probable surface structures, and their electronicand thermal energies were used to calculate their contribution tothe surface composition under the temperature and pressureconditions relevant for CVD and ALD processes of these materials. The results show similarities between the group of materials witha similar NHxsurface structure present for all three. Comparison of the coverage showed that at low growth temperatures, thesurface is expected to be covered by NH2, while at high temperatures, most surface sites would be vacant. The surface structureswere all found to be the most stable on AlN and least stable on InN. These results are important for further investigations of thematerial growth mechanisms.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2022
National Category
Materials Chemistry
Identifiers
urn:nbn:se:liu:diva-184838 (URN)10.1021/acs.jpcc.2c00510 (DOI)000786685900008 ()
Note

Funding Agencies|Swedish foundation for Strategic Research through the project "Time-resolved low temperature CVD for III-nitrides" [SSF-RMA 15-0018]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at the Linkoping University (Faculty Grant SFO Mat LiU) [2009 00971]; Swedish Research Council (VR)Swedish Research Council

Available from: 2022-05-12 Created: 2022-05-12 Last updated: 2023-02-24
5. Thermal study of an indium trisguanidinate as a possible indium nitride precursor
Open this publication in new window or tab >>Thermal study of an indium trisguanidinate as a possible indium nitride precursor
Show others...
2018 (English)In: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 36, no 1, article id 01A101Article in journal (Refereed) Published
Abstract [en]

Tris-N,N,-dimethyl-N,N -diisopropylguanidinatoindium(III) has been investigated both as a chemical vapor deposition precursor and an atomic layer deposition precursor. Although deposition was satisfactory in both cases, each report showed some anomalies in the thermal stability of this compound, warrenting further investigation, which is reported herein. The compound was found to decompose to produce diisopropylcarbodiimide both by computational modeling and solution phase nuclear magnetic resonance characterization. The decomposition was shown to have an onset at approximately 120 degrees C and had a constant rate of decomposition from 150 to 180 degrees C. The ultimate decomposition product was suspected to be bisdimethylamidoN, N,-dimethyl-N,N -diisopropylguanidinato-indium(III), which appeared to be an intractable, nonvolatile polymer. Published by the AVS.

Place, publisher, year, edition, pages
A V S AMER INST PHYSICS, 2018
National Category
Inorganic Chemistry
Identifiers
urn:nbn:se:liu:diva-144248 (URN)10.1116/1.5002634 (DOI)000418961400001 ()
Note

Funding Agencies|Swedish foundation for Strategic Research through the project "Time-resolved low temperature CVD for III-nitrides" [SSF-RMA15-0018]; COST Action [MP1402]; COST (European Cooperation in Science and Technology); Vinnova VINNMER Marie Curie incoming mobility program (Vinnova Grant) [2015-03714]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University (Faculty Grant SFO Mat LiU) [2009 00971]; Swedish Research Council (VR Grant) [2016-05137_4]; Wenner-Gren foundations

Available from: 2018-01-12 Created: 2018-01-12 Last updated: 2023-02-24

Open Access in DiVA

fulltext(4912 kB)499 downloads
File information
File name FULLTEXT01.pdfFile size 4912 kBChecksum SHA-512
74f9112f34589b6202b6ee9b9c5d29804ba93f6e60b5e5a8d505f19a9f16559dde9436212c7700d1aaf76e5e55cd65fbdbbfa699d46433a25a9ec55e99888a91
Type fulltextMimetype application/pdf
Order online >>

Other links

Publisher's full text

Authority records

Rönnby, Karl

Search in DiVA

By author/editor
Rönnby, Karl
By organisation
ChemistryFaculty of Science & Engineering
Materials Chemistry

Search outside of DiVA

GoogleGoogle Scholar
Total: 500 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

doi
isbn
urn-nbn

Altmetric score

doi
isbn
urn-nbn
Total: 1353 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf