Πτυχιακές εργασίες
Τρέχουσα Εγγραφή: 24 από 179
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| Τίτλος |
On the design of InN nano-heterostructures for field-effect transistors |
| Άλλος τίτλος |
Μελέτη της σχεδίασης νανο-ετεροδομών InN για τρανζίστορ επίδρασης πεδίου |
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Συγγραφέας
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Αστέρης, Αίας
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Σύμβουλος διατριβής
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Γεωργακίλας, Αλέξανδρος
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| Περίληψη |
InN is a III-V semiconductor with a small electron effective mass, high electron mobility and the highest electron drift velocity ever reported in solid-state devices. InN is thus a prominent candidate for the channel of field-effect transistors (FETs) that operate in the terahertz region. The realization of InN-based FETs, however, is hindered by several impediments; surface electron accumulation due to InN surface states, high bulk electron concentration, and crystal defects introduced by the large lattice mismatch between InN and potential substrates. Polarization in InN heterostructures significantly affects electron distribution within InN, too. In an attempt to better understand planar heterostructures for III-nitride FETs, self-consistent Schrödinger-Poisson (SCSP) calculations have been implemented for the equilibrium energy band and charge distribution profiling of InN channels on GaN, AlN and In0.8Al0.2N (0001) buffer layers. Metal-Insulator-Semiconductor (MIS) structures have also been investigated, using Si3N4, HfO2, Al2O3, or SiO2 as the insulator. The polarization-induced charge at the InN/AlN-buffer interface contributes to the channel depletion of electrons, yet favors hole accumulation near said interface. The two-dimensional hole gas could be prevented by assuming a positive charge contribution by misfit dislocations, equal to +1e per 5 nm of dislocation line. The formation of MIS systems facilitates channel electron depletion, with depletion efficiency increasing with insulator dielectric constant. Considering a compressively strained InN film on In0.8Al0.2N buffer layer yields similar results with the case of the AlN buffer. The pseudomorphic InN growth would reduce the density of crystal defects that degrade the electron transport properties in the InN layers, rendering the incorporation of the In0.8Al0.2N buffer preferable. Ultra-thin, continuous 2-5 nm InN films have been successfully grown on GaN and AlN (0001) buffer layers by plasma-assisted molecular beam epitaxy (PA-MBE). In-situ streaky RHEED patterns and post-growth AFM measurements indicated two-dimensional, step-flow growth and atomic-smooth surfaces.
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| Γλώσσα |
Αγγλικά |
| Ημερομηνία έκδοσης |
2023-07-28 |
| Συλλογή
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Σχολή/Τμήμα--Σχολή Θετικών και Τεχνολογικών Επιστημών--Τμήμα Φυσικής--Πτυχιακές εργασίες
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Τύπος Εργασίας--Πτυχιακές εργασίες
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| Μόνιμη Σύνδεση |
https://elocus.lib.uoc.gr//dlib/8/7/2/metadata-dlib-1689228177-548063-8693.tkl
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| Εμφανίσεις |
215 |
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