Improved NPIN Junctions for 100 GHz InP Mach-Zehnder Modulators
Bibliographic record
Abstract
High-bandwidth (>100 GHz) and compact indium phosphide Mach-Zehnder modulators with npin junctions, designed for low contact resistance, can experience parasitic photocurrent self-amplification, leading to unpredictable performance. This work introduces a design modification to address self-amplification by inserting a new n-doped material at the np-junction. This material has a lower conduction-bandenergy-minimum than the neighboring layers, thereby increasing the barrier to electron flow across the npin junction. Mach-Zehnder modulators fabricated with this modification demonstrate a 20% reduction in self-amplification compared to unmodified devices. Moreover, the modification improves performance consistency, decreasing the standard deviation of measured self-amplification across devices from 14% to 5%. Using a calibrated model, we identify the electron-hole recombination lifetime due to defects within the p-doped layer as a key factor influencing self-amplification. Our model, which includes perimeter-induced short lifetimes of 7 ps in the p-doped layer reproduces the experimental results. Furthermore, the model predicts that devices with well passivated sidewalls resulting in lifetimes of 10 ns will have a self-amplification exceeding 20 unless the modification is incorporated, in which case self-amplification is 1.5. The contact resistance of npin structures is verified to be two orders of magnitude lower than that of corresponding pin structures.
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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 | 0.000 |
| 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) | 0.000 | 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".