Oxygen vacancy induced phase and conductivity transition of epitaxial BaTiO3−δ films directly grown on Ge (001) without surface passivation
Bibliographic record
Abstract
The heterogeneous epitaxial system of BaTiO3/Ge (BTO/Ge) is of great interest for both fundamental research and device applications, thanks to its quasi-lattice-matching feature and the integration of functional oxides on semiconductors. Currently, the heteroepitaxial growth of crystalline BTO films on Ge includes the utilization of ultrahigh vacuum tools and complex surface passivation pre-treatment as well as careful control of oxygen partial pressure during the growth. Meanwhile, oxygen vacancies in oxides strongly impact their structural and electrical properties. Here, we report a facile method to directly grow single crystalline BTO films on Ge using pulsed laser deposition. The strict control of oxygen partial pressure ensures a sharp interface with an atom-to-atom registry and also leads to the oxygen-deficient characteristics of BTO. The epitaxial relationship of BTO and Ge is [110] BTO (001)//[100] Ge (001). Detailed crystallographic studies on BTO films with different thicknesses show that, for the films with a thickness less than 20 nm, BTO shows a mixture of tetragonal and cubic phases due to the oxygen vacancies and the strain from the Ge substrate and the cubic phase eventually dominates as the film thickness increases. Such oxygen-deficient BTO films reveal conducting characteristics rather than dielectric properties. The oxygen vacancies can be partly “cured” after a low temperature annealing process. These results not only demonstrate the possibility to directly grow single crystalline oxides on semiconductors without surface passivation but also highlight the importance of oxygen vacancies and lattice strain on the crystallographic and electrical properties of BTO films.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".