Studies of oxide desorption from GaAs substrates via Ga2O3 to Ga2O conversion by exposure to Ga flux
Bibliographic record
Abstract
Removal of the native oxide from GaAs wafers in the process of thermal desorption in the presence of As flux causes very significant surface degradation. We examine the merits of an alternative oxide desorption method that consists in a standard thermal oxide removal procedure preceded by a partial oxide removal at lower temperatures via conversion of the stable Ga2O3 surface oxide into a volatile Ga2O oxide by a pulsed supply of Ga in the absence of As flux. We find that a reduction of the substrate roughness by more than one order of magnitude is obtained on most epi-ready GaAs substrates regardless of their age, even if only 70% of the original gallium oxide is removed with Ga pulses, and that nearly atomically smooth surfaces are obtained with 90% oxide removal. In addition, we demonstrate that the Ga-induced oxide removal process is laterally inhomogeneous, making this method vulnerable to the accumulation of Ga droplets on the GaAs surface when more than about 90% of the surface oxide is removed. The Ga2O desorption pattern monitored with quadrupole mass spectrometry indicates that other nonvolatile species initially present on the top of the gallium oxide are also converted to a volatile species by Ga exposure before large areas of Ga2O3 become exposed. We examine the residual surface contamination left at the substrate–epilayer interface and find no significant influence of the age of the substrate, or the oxide removal method, on the measured levels of silicon, oxygen, and carbon.
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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".