Fabrication and Physics-Based Modeling of Polar AlGaN/GaN and AlInGaN/GaN HFETs
Notice bibliographique
Résumé
Since their advent, polar AlGaN/GaN hetero-junction field effect transistors (HFETs) have drawn a great deal of attention especially in high frequency/high power applications. However, the superb prospects of these transistors are affected by a few drawbacks such as aging/crack formation under strain, presence of high gate-leakage, and challenging realization of enhancement-mode (normally-off) devices. \nQuite recently, study of quaternary AlInGaN barriers has been presented as a promising avenue for fulfilling various design demands including: lattice matching, polarization matching, and positive shifting the inherently negative threshold voltage of AlGaN/GaN HFETs. However, thus far only a limited scope of theoretical studies on AlInGaN/GaN hetero-structure characteristics has been reported. As part of this thesis, the two dimensional electron gas (2DEG) characteristics of gated metal-face wurtzite AlInGaN/GaN hetero-junctions as function of physical and compositional properties of the hetero-junction are theoretically evaluated using the variational method. According to this study, a considerable shift in the positive direction for the threshold voltage of AlInGaN/GaN HFETs can be achieved by engineering both the spontaneous and the piezoelectric polarization (using a quaternary AlInGaN barrier-layer of appropriate mole-fractions). Succeeding this study, a novel quaternary lattice-match layer structure based on employing a bilayer barrier for improving the carrier confinement in the channel of enhancement-mode AlInGaN/GaN HFETs is for the first time proposed. It is shown that while the proposed layer structure substantially improves the carrier confinement in the GaN channel layer, it also upholds the merits of employing a lattice-match barrier towards achieving an enhancement-mode operation. \nOne of the most important device characteristics of AlGaN/GaN HFETs which is often poorly understood is the gate-leakage current. As part of this thesis, reverse gate-leakage of AlGaN/GaN HFETs is studied over a wide range of lattice-temperatures. While unveiling an obscure path for gate leakage through the mesa sidewall, a model considering different leakage paths, including the identified sidewall leakage, is presented. It is illustrated that the sidewall path to the 2DEG is associated with the Poole-Frenkel electron emission. The novel contribution of the present analysis is that it postulates that in absence of absolute uniformity, Fowler-Nordheim (FN) tunneling takes place through only a small portion of the surface of the barrier, which boasts the highest electric field or the smallest Schottky barrier height. This consideration, allows the model to avoid unrealistic values for quantities such as effective electron mass (that has plagued many of the existing models). \nAlso as part of this thesis work, process recipe for microfabrication of submicron gate AlGaN/GaN HFETs using electron beam lithography was developed at McGill’s nano-tools micro-fabrication facilities. The results of DC characterization of the fabricated transistors along with the results of the DC stress test are presented.
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
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Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,000 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule tête enseignante, pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».