Growth characteristics of vacuum coated thick <i>a</i>-Se films for device applications
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Bibliographic record
Abstract
There has been a resurgence of interest in the growth characteristics of amorphous Se (a-Se) films due to their recently commercialized applications in x-ray imaging as x-ray photoconductors. Electronic quality a-Se films require the substrate temperature during vacuum deposition to be as high as possible but increasing the substrate temperature leads to amorphous films containing crystalline inclusions and eventually to polycrystalline films which have high conductivity and are therefore not useful as photoconductors. We prepared a variety of thick a-Se films on Al substrates by conventional vacuum deposition in which only the substrate temperature Tsb and boat temperature Tbt were varied. Experiments indicated the appearance of crystalline zones (crystallites) in the amorphous Se film as the substrate temperature was increased. We identified an experimental critical Tbt−Tsb boundary between amorphous films with and without crystalline inclusions. A model has been developed for the critical relationship between Tsb and Tbt, i.e., Tbt=f(Tsb) based on two competing rate mechanisms: the rate of deposition (or material condensation on the substrate) and rate of crystal growth in the film assuming heterogeneous nucleation at favorable substrate sites. Over the narrow substrate temperature range, we approximated the Vogel–Tamman–Fulcher behavior of the crystal growth rate by an Arrhenius rate with an apparent activation energy Ecr that accounts for most crystallization studies on a-Se. The condensation rate was assumed to follow an Arrhenius rate with the activation energy determined by the enthalpy of evaporation, Eev. The Tbt=f(Tsb) model was particularly sensitive to the Ecr/Eev ratio. By using the presently accepted values for Eev and Ecr, it was shown that the experimental results could be well fitted to the Tbt=f(Tsb) model. The results have a wider significance than a-Se and can be easily extended to apply to a number of other chalcogenide semiconductor films.
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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 | 0.002 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.001 | 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 it