Effects of stoichiometry and individual layer thickness ratio on the quality of epitaxial CrBx/TiBy superlattice thin films
Studies of single crystal artificial superlattices (SLs) of transition-metal (TM) diborides, which is instrumental to understand hardening mechanisms at nanoscale, is lacking. Here, CrBx/TiBy (0001) diboride SLs [x,y ∈ 1.7–3.3] are grown epitaxially on Al2O3(0001) substrates by direct-current magnet...
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| Format: | Article |
| Language: | English |
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Elsevier
2023-04-01
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| Series: | Materials & Design |
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| Online Access: | http://www.sciencedirect.com/science/article/pii/S0264127523002575 |
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| author | Samira Dorri Jens Birch Fredrik Eriksson Justinas Palisaitis Per O.Å. Persson Babak Bakhit Lars Hultman Naureen Ghafoor |
| author_facet | Samira Dorri Jens Birch Fredrik Eriksson Justinas Palisaitis Per O.Å. Persson Babak Bakhit Lars Hultman Naureen Ghafoor |
| author_sort | Samira Dorri |
| collection | DOAJ |
| description | Studies of single crystal artificial superlattices (SLs) of transition-metal (TM) diborides, which is instrumental to understand hardening mechanisms at nanoscale, is lacking. Here, CrBx/TiBy (0001) diboride SLs [x,y ∈ 1.7–3.3] are grown epitaxially on Al2O3(0001) substrates by direct-current magnetron sputter epitaxy. Growth conditions for obtaining well-defined SLs with good interface quality are found at 4 mTorr Ar pressure and 600 °C. 1-µm-thick SL films deposited with modulation periods Λ between 1 and 10 nm, and Λ = 6 nm SLs with TiBy-to-Λ layer thickness ratios Γ ranging from 0.2 to 0.8 are studied. SLs with Λ = 6 nm and Γ in the range of 0.2–0.4, with a near stoichiometric B/TM ratio, exhibit the highest structural quality. The effects of Γ and stoichiometries (B/TM ratio) on the distribution of B in the SL structures are discussed. By increasing the relative thickness of TiBy, the crystalline quality of SLs starts to deteriorate due to B segregation in over-stoichiometric TiBy, resulting in narrow epitaxial SL columnar growth with structurally-distorted B-rich boundaries. Moreover, increasing the relative thickness of under-stoichiometric CrBx enhances the SL quality and hinders formation of B-rich boundaries. The SLs are found to exhibit hardness values in the range of 29–34 GPa. |
| first_indexed | 2024-04-09T17:14:06Z |
| format | Article |
| id | doaj.art-b496c57d1111447e852a59a4291d7146 |
| institution | Directory Open Access Journal |
| issn | 0264-1275 |
| language | English |
| last_indexed | 2024-04-09T17:14:06Z |
| publishDate | 2023-04-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Materials & Design |
| spelling | doaj.art-b496c57d1111447e852a59a4291d71462023-04-20T04:35:21ZengElsevierMaterials & Design0264-12752023-04-01228111842Effects of stoichiometry and individual layer thickness ratio on the quality of epitaxial CrBx/TiBy superlattice thin filmsSamira Dorri0Jens Birch1Fredrik Eriksson2Justinas Palisaitis3Per O.Å. Persson4Babak Bakhit5Lars Hultman6Naureen Ghafoor7Corresponding author.; Thin Film Physics Division, Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-581 83 Linköping, SwedenThin Film Physics Division, Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-581 83 Linköping, SwedenThin Film Physics Division, Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-581 83 Linköping, SwedenThin Film Physics Division, Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-581 83 Linköping, SwedenThin Film Physics Division, Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-581 83 Linköping, SwedenThin Film Physics Division, Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-581 83 Linköping, SwedenThin Film Physics Division, Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-581 83 Linköping, SwedenThin Film Physics Division, Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-581 83 Linköping, SwedenStudies of single crystal artificial superlattices (SLs) of transition-metal (TM) diborides, which is instrumental to understand hardening mechanisms at nanoscale, is lacking. Here, CrBx/TiBy (0001) diboride SLs [x,y ∈ 1.7–3.3] are grown epitaxially on Al2O3(0001) substrates by direct-current magnetron sputter epitaxy. Growth conditions for obtaining well-defined SLs with good interface quality are found at 4 mTorr Ar pressure and 600 °C. 1-µm-thick SL films deposited with modulation periods Λ between 1 and 10 nm, and Λ = 6 nm SLs with TiBy-to-Λ layer thickness ratios Γ ranging from 0.2 to 0.8 are studied. SLs with Λ = 6 nm and Γ in the range of 0.2–0.4, with a near stoichiometric B/TM ratio, exhibit the highest structural quality. The effects of Γ and stoichiometries (B/TM ratio) on the distribution of B in the SL structures are discussed. By increasing the relative thickness of TiBy, the crystalline quality of SLs starts to deteriorate due to B segregation in over-stoichiometric TiBy, resulting in narrow epitaxial SL columnar growth with structurally-distorted B-rich boundaries. Moreover, increasing the relative thickness of under-stoichiometric CrBx enhances the SL quality and hinders formation of B-rich boundaries. The SLs are found to exhibit hardness values in the range of 29–34 GPa.http://www.sciencedirect.com/science/article/pii/S0264127523002575DiboridesSuperlatticesThin filmsThickness ratioModulation periodStoichiometry |
| spellingShingle | Samira Dorri Jens Birch Fredrik Eriksson Justinas Palisaitis Per O.Å. Persson Babak Bakhit Lars Hultman Naureen Ghafoor Effects of stoichiometry and individual layer thickness ratio on the quality of epitaxial CrBx/TiBy superlattice thin films Materials & Design Diborides Superlattices Thin films Thickness ratio Modulation period Stoichiometry |
| title | Effects of stoichiometry and individual layer thickness ratio on the quality of epitaxial CrBx/TiBy superlattice thin films |
| title_full | Effects of stoichiometry and individual layer thickness ratio on the quality of epitaxial CrBx/TiBy superlattice thin films |
| title_fullStr | Effects of stoichiometry and individual layer thickness ratio on the quality of epitaxial CrBx/TiBy superlattice thin films |
| title_full_unstemmed | Effects of stoichiometry and individual layer thickness ratio on the quality of epitaxial CrBx/TiBy superlattice thin films |
| title_short | Effects of stoichiometry and individual layer thickness ratio on the quality of epitaxial CrBx/TiBy superlattice thin films |
| title_sort | effects of stoichiometry and individual layer thickness ratio on the quality of epitaxial crbx tiby superlattice thin films |
| topic | Diborides Superlattices Thin films Thickness ratio Modulation period Stoichiometry |
| url | http://www.sciencedirect.com/science/article/pii/S0264127523002575 |
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