Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • 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
Characterisation of high-temperature annealing effects on alpha-Al2O3(0001) substrates
Show others and affiliations
2008 (English)In:  PROCEEDINGS OF THE 17TH INTERNATIONAL VACUUM CONGRESS/13TH INTERNATIONAL CONFERENCE ON SURFACE SCIENCE/INTERNATIONAL CONFERENCE ON NANOSCIENCE AND TECHNOLOGY    / [ed] Johansson LSO; Andersen JN; Gothelid M; Helmersson U; Montelius L; Rubel M; Setina J; Wernersson LE, 2008, Vol. 100Conference paper, Published paper (Refereed)
Abstract [en]

High temperature annealing in air has been applied as an effective ex-situ surface treatment for the alpha-Al2O3(0001) substrates used in molecular beam epitaxy (MBE) growth of III-nitrides. The method is based on the criterion that atomically smooth surface of terrace-and-step like structure, which is considered to be crucial in obtaining a high quality epilayer, could be produced upon high temperature annealing. The annealed surface was mostly studied by atomic force microscopy (AFM) imaging. In this work, the effects of high temperature annealing on the surface morphology, crystalline quality, optical quality and surface reconstruction behaviour of alpha-Al2O3(0001) substrates were fully studied using AFM, triple-axis high resolution X-ray diffraction (THRXRD), spectroscopic ellipsometry (SE) and insitu reflection high-energy electron diffraction (RHEED). A new strategy, H-2 thermal cleaning at 1100 degrees C followed by O-2 annealing at 1300 degrees C was proposed as an efficient surface treatment for alpha-Al2O3 (0001) substrates for MBE growth.

Place, publisher, year, edition, pages
2008. Vol. 100
Series
Journal of Physics Conference Series, ISSN 1742-6588 ; 100
Keyword [en]
AFM, Atomically smooth surface, Characterisation, Crystalline quality, Efficient surface, Ex situ, High quality, High resolution X ray diffraction, High-temperature annealing, III-nitrides, In-situ, MBE growth, New strategy, Optical qualities, Thermal cleaning
National Category
Condensed Matter Physics
Identifiers
URN: urn:nbn:se:kth:diva-25035DOI: 10.1088/1742-6596/100/4/042020ISI: 000275655200068OAI: oai:DiVA.org:kth-25035DiVA: diva2:355204
Conference
17th International Vacuum Congress/13th International Conference on Surface Science/Internatinal Conference on Nanoscience and Technology. Stockholm, SWEDEN, JUL 02-06, 2007
Note
QC 20101006Available from: 2010-10-06 Created: 2010-10-06 Last updated: 2010-10-06Bibliographically approved
In thesis
1. Surface studies on α–sapphire for potential use in GaN epitaxial growth
Open this publication in new window or tab >>Surface studies on α–sapphire for potential use in GaN epitaxial growth
2009 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

This Licentiate thesis summarizes the work carried out by the author the years 2004 to 2008 at the University of Iceland and the Royal Institute of Technology (KTH) in Sweden. The aim of the project was to investigate the structure of sapphire (alpha-Al2O3) surfaces, both for pure scientific reasons and also for potential use as substrate for GaN-growth by molecular beam epitaxy.

More generally the thesis describes some surface science methods used for investigating the substrates; the general physical back ground, the experi- mental implementation and what information they can give. The described techniques are used for surface analysis on sapphire substrates which have been treated variously in order to optimize them for use as templates for epi- taxial growth of GaN or related III-V compounds.

The thesis is based on three published papers.

The first paper focuses on the formation a thin AlN layer on sapphire, which may act as a buffer layer for potential epitaxial growth of GaN or any related III-V materials. Two types of sapphire substrates (reconstructed and non- reconstructed) were exposed to ammonia resulting in the formation of AlN on the surface. The efficiency of the AlN formation (nitridation efficiency) for the two surfaces was then compared as a function of substrate temperature through photoelectron spectroscopy and low electron energy diffraction. The reconstructed surface showed a much higher nitridation efficiency than the non-reconstructed surface.

In the second paper, the affect of different annealing processes on the sapphire morphology, and thus its capability to act as a template for GaN growth, was studied. Atomic force microscopy, X-ray diffraction analysis together with ellipsometry measurements showed that annealing in H2 ambient and subse- quent annealing at 1300 °C in O2 for 11 hours resulted in high quality and atomically flat sapphire surface suitable for III-V epitaxial growth.

The third paper describes the effect of argon sputtering on cleaning GaN surfaces and the possibility of using indium as surfactant for establishing a clean and stoichiometric GaN surface, after such sputtering. Soft sputtering, followed by deposition of 2 ML of indium and subsequent annealing at around 500 °C resulted in a well ordered and clean GaN surface while hard sputtering introduced defects and incorporated both metallic gallium and indium in the surface.

Place, publisher, year, edition, pages
KTH, 2009. xi, 49 p.
Series
Trita-ICT/MAP, 2009:3
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:kth:diva-10669 (URN)978-91-7415-286-9 (ISBN)
Presentation
2009-06-05, Sal/Hall C1, KTH-Electrum, Isafjordsgatan 26, Kista, 10:15 (English)
Opponent
Supervisors
Available from: 2009-06-22 Created: 2009-06-13 Last updated: 2010-11-03Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full text

Search in DiVA

By author/editor
Agnarsson, Björn
Condensed Matter Physics

Search outside of DiVA

GoogleGoogle Scholar

doi
urn-nbn

Altmetric score

doi
urn-nbn
Total: 135 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • 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