Atomic networks as highways for holes in oxygen-deficient amorphous oxides
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arXiv
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| Format: | Preprint |
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2025
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| _version_ | 1866916982324985856 |
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| author | Costa-Amaral, Rafael Kumagai, Yu |
| author_facet | Costa-Amaral, Rafael Kumagai, Yu |
| contents | Oxygen-deficient amorphous tellurium oxides ($a$-TeO$_x$) have recently challenged the intrinsic hole mobility limits of amorphous oxides, with thin-film transistors reaching mobilities up to 15 cm$^{2}$V$^{-1}$s$^{-1}$ upon Se doping. However, the atomistic origins of this behavior, and its seeming contradiction with established semiconductor physics, have remained unresolved. Here, we combine machine-learning-accelerated ab initio molecular dynamics with hybrid-functional defect calculations to establish a new microscopic picture. We show that substantial oxygen loss drives spontaneous segregation into interpenetrating $a$-Te and $a$-TeO$_2$ domains, rather than forming dispersed oxygen vacancies. The diffuse Te-$5p$ states from the $a$-Te network supply percolative pathways for holes, so mobility rises monotonically with oxygen deficiency, enabling mobilities that exceed current records. Doped Se incorporates into the $a$-Te domain, enhancing the connectivity of conductive pathways, thereby increasing hole mobility. Similar behavior in amorphous SeO$_x$ suggests domain percolation as a general route to high-mobility p-type transport in amorphous oxides. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2510_00473 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Atomic networks as highways for holes in oxygen-deficient amorphous oxides Costa-Amaral, Rafael Kumagai, Yu Materials Science Mesoscale and Nanoscale Physics Oxygen-deficient amorphous tellurium oxides ($a$-TeO$_x$) have recently challenged the intrinsic hole mobility limits of amorphous oxides, with thin-film transistors reaching mobilities up to 15 cm$^{2}$V$^{-1}$s$^{-1}$ upon Se doping. However, the atomistic origins of this behavior, and its seeming contradiction with established semiconductor physics, have remained unresolved. Here, we combine machine-learning-accelerated ab initio molecular dynamics with hybrid-functional defect calculations to establish a new microscopic picture. We show that substantial oxygen loss drives spontaneous segregation into interpenetrating $a$-Te and $a$-TeO$_2$ domains, rather than forming dispersed oxygen vacancies. The diffuse Te-$5p$ states from the $a$-Te network supply percolative pathways for holes, so mobility rises monotonically with oxygen deficiency, enabling mobilities that exceed current records. Doped Se incorporates into the $a$-Te domain, enhancing the connectivity of conductive pathways, thereby increasing hole mobility. Similar behavior in amorphous SeO$_x$ suggests domain percolation as a general route to high-mobility p-type transport in amorphous oxides. |
| title | Atomic networks as highways for holes in oxygen-deficient amorphous oxides |
| topic | Materials Science Mesoscale and Nanoscale Physics |
| url | https://arxiv.org/abs/2510.00473 |