Enhancement of Local Terahertz Electric Field by a Semiconductor Nano-Dumbbell
Bibliographic record
Abstract
Semiconductor nanoparticles (SNP) are of current interest for applications in the terahertz frequency range owing to their surface plasmon resonance (SPR) frequency being amenable to be situated in the terahertz range by doping. They can play roles in the terahertz range similar to those of metallic nanoparticles in the optical region. With a lower charge carrier concentration in extrinsic semiconductors, space-charge effects are more prevalent in SNP than in their metallic counterparts. A transport formulation for carrier dynamics is necessary to provide realistic accounts of the charge distribution and the internal field in an SNP polarized by an externally applied terahertz electric field (T. Shen, M. Yan, and T. Wong, “Charge Polarization and Current Distribution in a Conductive Particle in the Rayleigh Region”, IEEE Trans. Antennas and Propagation, v. 61, pp. 4229–4238, Aug. 2013). Clusters of SNP can be formed to intensify the effects of their polarization. A particle pair (dimer) is the simplest form of cluster of fundamental interest to gain insight to interactions between particles in terms of shift in SPR frequency and local field enhancement. The potential of a non-overlapping semiconductor nanodimer (SND) as a scanning sensor in the terahertz range has been studied (Z. Wang and T. Wong, “Field Dynamics in the Gap of a Semiconductor Nanodimer,” Proc. IEEE NANO, 2021, pp. 414–417, Montreal, July, 2021). A surface or substrate is required to anchor the two SNPs to maintain the gap spacing between them for a non-overlapping SND. In a fluidic environment, it is more practical to have a single nanostructure to perform functional tasks such as field enhancement and sensing. For these purposes, the semiconductor nano-dumbbell (SNDB) may be employed. It is actually an SND in the overlapping regime but for better visualization of the geometry, the dumbbell shape is emphasized in its nomenclature. In this paper, field simulation for an SNDB polarized by a terahertz electric field employing a transport formulation to reveal the space-charge interaction is reported. Results indicate that two orders of magnitude in field enhancement at the SPR frequency is accomplished at the waist of the SNDB, as shown in the figure, in which the field surrounding a single SNP of same radius and a semiconductor nanorod with same axial length as that of the SNDB are also displayed for comparison. The strong enhancement action of the SNDB is attributed to the presence of space charge of opposite polarities on two sides of the wedge structure at the waist of the SNDB, while opposite charges on the SNP and on the nanorod are concentrated at locations which are much farther apart from each other.
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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 | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.001 |
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".