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Identifier |
000399721 |
Title |
Έλεγχος της πολικότητας επιταξιακού GaN πάνω σε υπόστρωμα Si(111) |
Alternative Title |
Control of GaN polarity on Si(111) substrate |
Author
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Τσικριτσάκη, Ελευθερία Ι.
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Thesis advisor
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Γεωργακίλας, Αλέξανδρος
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Reviewer
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Ηλιόπουλος, Ελευθέριος
Χατζόπουλος, Ζαχαρίας
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Abstract |
The aim of this work is the control of III-Nitrides polarity on Si (111) substrates grown by plasma
assisted molecular beam epitaxy (PAMBE). Depended on the applications, may be desirable
Ga-face or N-face polarity. Two different groups of samples of thin films GaN (0001) were grown
on Si (111) substrates. On those samples, not only growth conditions but also thickness of an
initial nucleation layer AlN on the surface of the silicon substrate was changed. Their
effectiveness on polarity, surfaces’ morphology, crystalline quality and electrical caracteristics of
the growing material was examined. On the different AlN nucleation layers, the temperature of
the substrate, the Al/N ratio of incident flow and the thickness of the AlN layer, were changed.
On those thin films, HEMT AlN/GaN and AlGaN/GaN heterostructures were grown, so as to
achieve the formation of a two dimensional electron gas (2DEG). The determination of GaN
layers polarity was based on selective etching of N-face GaN, by dipping in KOH solution. It was
also examined the occurence of C-V measurements, in order to define formation and place of
2DEG on heterostructures. Definition of polarity of epitaxial layers of those experiments showed
that Ga-face polarity is achieved when AlN nucleation layer is used up to 2nm thickness. G-face
polarity can be also achieved with an AlN nucleation layer of bigger thickness when it is grown
on low temperature and N-rich conditions. N-face polarity is achieved by the growth of AlN
nucleation layers with thickness of twenty-fifty nm on stichiometric conditions Al/N. Polarity of
GaN layers and growth conditions of AlN nucleation layers, affected the morphology of the
surface, the total crystalline quality and the electrical characteristics of GaN heterostructures.
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Language |
Greek |
Subject |
HEMT |
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III-Nitrides |
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III-Νιτρίδια |
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MBE |
Issue date |
2016-03-18 |
Collection
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School/Department--School of Sciences and Engineering--Department of Physics--Post-graduate theses
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Type of Work--Post-graduate theses
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Permanent Link |
https://elocus.lib.uoc.gr//dlib/7/9/a/metadata-dlib-1456757515-302223-19056.tkl
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Views |
534 |