Amorphous selenium direct detection CMOS digital x-ray imager with 25 micron pixel pitch
Bibliographic record
Abstract
ABSTRACT We have developed a high resolution amorphous selenium (a-Se) direct detection imager using a large-areacompatible back-end fabrication process on top of a CMOS active pixel sensor having 25 micron pixel pitch.Integration of a-Se with CMOS technology requires overcoming CMOS/a-Se interfacial strain, which initiatesnucleation of crystalline selenium and results in high detector dark currents. A CMOS-compatible polyimidebu er layer was used to planarize the backplane and provide a low stress and thermally stable surface for a-Se.The bu er layer inhibits crystallization and provides detector stability that is not only a performance factor butalso critical for favorable long term cost-bene t considerations in the application of CMOS digital x-ray imagersin medical practice. The detector structure is comprised of a polyimide (PI) bu er layer, the a-Se layer, and agold (Au) top electrode. The PI layer is applied by spin-coating and is patterned using dry etching to open thebackplane bond pads for wire bonding. Thermal evaporation is used to deposit the a-Se and Au layers, and thedetector is operated in hole collection mode (i.e. a positive bias on the Au top electrode).High resolution a-Se diagnostic systems typically use 70 to 100 m pixel pitch and have a pre-samplingmodulation transfer function (MTF) that is signi cantly limited by the pixel aperture. Our results con rm that,for a densely integrated 25 m pixel pitch CMOS array, the MTF approaches the fundamental material limit,i.e. where the MTF begins to be limited by the a-Se material properties and not the pixel aperture. Preliminaryimages demonstrating high spatial resolution have been obtained from a rst prototype imager.Keywords: x-ray imaging, high spatial resolution, amorphous selenium, CMOS, CMOS-selenium, array pro-cessing, direct conversion, at panel imaging
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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) | 0.001 | 0.001 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| 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".