Passivation of GaAs by octadecanethiol self-assembled monolayers deposited from liquid and vapor phases
Bibliographic record
Abstract
Self-assembled monolayers (SAMs) of octadecanethiol (ODT), CH3(CH2)17SH, were deposited on GaAs (100) substrates from liquid and vapor phases. Liquid-phase-deposited SAMs were prepared by immersing the substrate in a dilute solution of ODT and ethanol, while vapor-phase-deposited monolayers were prepared by exposing the GaAs surface to a stream of ODT vapor in an ultrahigh vacuum environment. The structural and optical properties of the resulting SAMs were examined with contact angle (CA) analysis, photoluminescence (PL) spectroscopy, high-resolution x-ray photoelectron spectroscopy (HRXPS), and spectroscopic ellipsometry. Although well-ordered films were formed from both deposition techniques, PL, CA analysis, and ellipsometry measurements revealed that the overall quality, structure, and long-term durability of the resulting SAMs depended on the preparation method. Specifically, time-dependent PL and CA analysis indicated an enhanced stability for vapor-deposited films stored under ambient conditions. Through HRXPS measurements, the attachment of the thiolate molecules to the GaAs substrates was shown to proceed through the formation of chemical bonds at both Ga and As surface sites, with the percentage of each bonding configuration dictated by the surface termination produced via the cleaning process used prior to the SAM deposition. Collectively, the results suggested that more robust monolayers exhibiting greater surface coverage, and therefore increased passivation and stability characteristics, are assembled from vapor phase.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| 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) | 0.000 | 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 teacher head, 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".