Effect of MgO Underlying Layer on the Growth of GaOx Tunnel Barrier in Epitaxial Fe/GaOx/(MgO)/Fe Magnetic Tunnel Junction Structure
We investigated the effect of a thin MgO underlying layer (~3 monoatomic layers) on the growth of GaOx tunnel barrier in Fe/GaOx/(MgO)/Fe(001) magnetic tunnel junctions. To obtain a single-crystalline barrier, an in situ annealing was conducted with the temperature being raised up to 500 °C under an...
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MDPI AG
2017-10-01
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| Series: | Sensors |
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| Online Access: | https://www.mdpi.com/1424-8220/17/10/2424 |
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| author | Sai Krishna Narayananellore Naoki Doko Norihiro Matsuo Hidekazu Saito Shinji Yuasa |
| author_facet | Sai Krishna Narayananellore Naoki Doko Norihiro Matsuo Hidekazu Saito Shinji Yuasa |
| author_sort | Sai Krishna Narayananellore |
| collection | DOAJ |
| description | We investigated the effect of a thin MgO underlying layer (~3 monoatomic layers) on the growth of GaOx tunnel barrier in Fe/GaOx/(MgO)/Fe(001) magnetic tunnel junctions. To obtain a single-crystalline barrier, an in situ annealing was conducted with the temperature being raised up to 500 °C under an O2 atmosphere. This annealing was performed after the deposition of the GaOx on the Fe(001) bottom electrode with or without the MgO(001) underlying layer. Reflection high-energy electron diffraction patterns after the annealing indicated the formation of a single-crystalline layer regardless of with or without the MgO layer. Ex situ structural studies such as transmission electron microscopy revealed that the GaOx grown on the MgO underlying layer has a cubic MgAl2O4-type spinel structure with a (001) orientation. When without MgO layer, however, a Ga-Fe-O ternary compound having the same crystal structure and orientation as the crystalline GaOx was observed. The results indicate that the MgO underlying layer effectively prevents the Fe bottom electrode from oxidation during the annealing process. Tunneling magneto-resistance effect was observed only for the sample with the MgO underlying layer, suggesting that Ga-Fe-O layer is not an effective tunnel-barrier. |
| first_indexed | 2024-04-13T06:11:43Z |
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| institution | Directory Open Access Journal |
| issn | 1424-8220 |
| language | English |
| last_indexed | 2024-04-13T06:11:43Z |
| publishDate | 2017-10-01 |
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| spelling | doaj.art-5ed16d2880f14e74bc62be8081d205582022-12-22T02:59:03ZengMDPI AGSensors1424-82202017-10-011710242410.3390/s17102424s17102424Effect of MgO Underlying Layer on the Growth of GaOx Tunnel Barrier in Epitaxial Fe/GaOx/(MgO)/Fe Magnetic Tunnel Junction StructureSai Krishna Narayananellore0Naoki Doko1Norihiro Matsuo2Hidekazu Saito3Shinji Yuasa4National Institute of Advanced Industrial Science and Technology (AIST), Spintronics Research Center, Umezono 1-1-1, Central 2, Tsukuba, Ibaraki 305-8568, JapanNational Institute of Advanced Industrial Science and Technology (AIST), Spintronics Research Center, Umezono 1-1-1, Central 2, Tsukuba, Ibaraki 305-8568, JapanNational Institute of Advanced Industrial Science and Technology (AIST), Spintronics Research Center, Umezono 1-1-1, Central 2, Tsukuba, Ibaraki 305-8568, JapanNational Institute of Advanced Industrial Science and Technology (AIST), Spintronics Research Center, Umezono 1-1-1, Central 2, Tsukuba, Ibaraki 305-8568, JapanNational Institute of Advanced Industrial Science and Technology (AIST), Spintronics Research Center, Umezono 1-1-1, Central 2, Tsukuba, Ibaraki 305-8568, JapanWe investigated the effect of a thin MgO underlying layer (~3 monoatomic layers) on the growth of GaOx tunnel barrier in Fe/GaOx/(MgO)/Fe(001) magnetic tunnel junctions. To obtain a single-crystalline barrier, an in situ annealing was conducted with the temperature being raised up to 500 °C under an O2 atmosphere. This annealing was performed after the deposition of the GaOx on the Fe(001) bottom electrode with or without the MgO(001) underlying layer. Reflection high-energy electron diffraction patterns after the annealing indicated the formation of a single-crystalline layer regardless of with or without the MgO layer. Ex situ structural studies such as transmission electron microscopy revealed that the GaOx grown on the MgO underlying layer has a cubic MgAl2O4-type spinel structure with a (001) orientation. When without MgO layer, however, a Ga-Fe-O ternary compound having the same crystal structure and orientation as the crystalline GaOx was observed. The results indicate that the MgO underlying layer effectively prevents the Fe bottom electrode from oxidation during the annealing process. Tunneling magneto-resistance effect was observed only for the sample with the MgO underlying layer, suggesting that Ga-Fe-O layer is not an effective tunnel-barrier.https://www.mdpi.com/1424-8220/17/10/2424magnetic tunnel junctionepitaxial growthgallium oxidetunneling magneto-resistancesemiconductor |
| spellingShingle | Sai Krishna Narayananellore Naoki Doko Norihiro Matsuo Hidekazu Saito Shinji Yuasa Effect of MgO Underlying Layer on the Growth of GaOx Tunnel Barrier in Epitaxial Fe/GaOx/(MgO)/Fe Magnetic Tunnel Junction Structure Sensors magnetic tunnel junction epitaxial growth gallium oxide tunneling magneto-resistance semiconductor |
| title | Effect of MgO Underlying Layer on the Growth of GaOx Tunnel Barrier in Epitaxial Fe/GaOx/(MgO)/Fe Magnetic Tunnel Junction Structure |
| title_full | Effect of MgO Underlying Layer on the Growth of GaOx Tunnel Barrier in Epitaxial Fe/GaOx/(MgO)/Fe Magnetic Tunnel Junction Structure |
| title_fullStr | Effect of MgO Underlying Layer on the Growth of GaOx Tunnel Barrier in Epitaxial Fe/GaOx/(MgO)/Fe Magnetic Tunnel Junction Structure |
| title_full_unstemmed | Effect of MgO Underlying Layer on the Growth of GaOx Tunnel Barrier in Epitaxial Fe/GaOx/(MgO)/Fe Magnetic Tunnel Junction Structure |
| title_short | Effect of MgO Underlying Layer on the Growth of GaOx Tunnel Barrier in Epitaxial Fe/GaOx/(MgO)/Fe Magnetic Tunnel Junction Structure |
| title_sort | effect of mgo underlying layer on the growth of gaox tunnel barrier in epitaxial fe gaox mgo fe magnetic tunnel junction structure |
| topic | magnetic tunnel junction epitaxial growth gallium oxide tunneling magneto-resistance semiconductor |
| url | https://www.mdpi.com/1424-8220/17/10/2424 |
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