Growth of high-performance GaN modulation-doped field-effect transistors by ammonia-molecular-beam epitaxy
Bibliographic record
Abstract
The growth of AlGaN/GaN modulation-doped field-effect transistors (MODFETs) by ammonia-molecular-beam epitaxy on sapphire substrates is reported. C-doped GaN (2 μm thick) was used as the insulating buffer layer in the device structures. The MODFET structure was completed by the subsequent growth of 2000 Å of undoped GaN as the channel layer and 130 Å of AlxGa1−xN(0.1⩽x⩽0.3) as the donor barrier layer. Sheet carrier densities of up to 2×1013 cm−2 with mobility of ∼1000 cm2/V s have been achieved even without doping the AlxGa1−xN barrier, indicating a large piezoelectric effect and excellent interface quality. The MODFET layers grown exhibited a unique surface morphology showing very flat plateaus with rms roughness of 0.8 nm on the plateaus and rms roughness of 8 nm over a larger area. A 100-μm-wide device with a 1 μm gate length exhibited a maximum dc current drive of 0.9 A/mm, a peak transconductance of 160 mS/mm, a current gain cutoff frequency of 15.6 GHz, and a maximum oscillation frequency of 49.4 GHz. The high dc and rf performance is attributed to the high two-dimensional electron mobility, high sheet charge density, and insulating property of the C-doped GaN buffer.
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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".