Role of hydrogen and annealing in enhancement of passivation at the a-Si:H/c-Si interface
Bibliographic record
Abstract
Hydrogenated amorphous silicon (a-Si:H) is an effective material for the passivation of crystalline silicon (c-Si) surface owing to its hydrogenation of Si dangling bonds at the interface and corresponding reduction in the recombination center density. The DC saddle-field (DCSF) glow discharge method was used to deposit intrinsic a-Si:H at different process temperatures (140 deg C - 220 deg C) onto 1-2 ohm-cm n-type FZ crystalline silicon (c-Si) substrates with <100> orientation and thickness of 280 microns. The effective minority carrier lifetime in the heterostructures as a function of the excess minority carrier density (ECD) in c-Si was measured for an ECD of 10^15 cm^-3. Fourier transform infrared spectroscopy was carried out on the films to obtain the total hydrogen content and the distribution of mono- and di-hydride structures SiHn (n=1, 2). Additionally, the influence of subsequent annealing of the samples was studied. The temperature of deposition has a significant bearing on the quality of the films grown. At process temperatures below 160 deg C, the species adsorbed on the surface during the plasma deposition process have a relatively low surface mobility and the diffusivity of hydrogen is reduced. Both effects result in an increased density of unsaturated bonds at the surface and hence a higher interface state density. Higher process temperatures (>180 deg C) also result in poor surface passivation due to low hydrogen content and higher defect density. The hydrogen content decreased from above 20 at.% for a-Si:H prepared at 140 deg C to 5 at.% for samples prepared at 200 deg C. Ratio of SiH2 to SiH increased from 1 to 20 over the same temperature range. At the optimum process temperature of 170 deg C, we achieved an effective carrier lifetime of 2 ms with a 30 nm a-Si:H passivating layer. Annealing the samples at 180 deg C significantly increases the effective lifetime. This increase is mainly attributed to the restructuring of silicon bonds at the a-Si:H/c-Si interface through the diffusion of hydrogen. Annealing also leads to restructuring and relaxation of the lattice which reduces the defect density by decreasing the concentration of strained Si-Si bonds.
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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 | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.003 | 0.001 |
| Science and technology studies | 0.000 | 0.002 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.002 |
| 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 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".