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CNAA / Theses / 2017 / May /

Two- and three-dimensional nanoarchitectures based on GaN for engineering applications


Author: Braniște Fiodor
Degree:doctor of engineering
Speciality: 05.27.01 - Solid State Electronics, Microelectronics and Nanoelectronics
Year:2017
Scientific adviser: Ion Tighineanu
doctor habilitat, professor, Institute of Mathematics and Computer Science of the ASM
Institution: Technical University of Moldova

Status

The thesis was presented on the 16 May, 2017
Approved by NCAA on the 31 May, 2017

Abstract

Adobe PDF document1.25 Mb / in romanian

Thesis

CZU 621.315.592

Adobe PDF document 9.55 Mb / in romanian
158 pages


Keywords

Nanotechnologies, GaN, nanomembranes, photonic crystals, sensors, endothelial cells, nanomedicine, living cells guiding

Summary

Thesis structure: The thesis was realized at the National Center for Materials Study and Testing, Technical University of Moldova, Chisinau, 2017. It is written in Romanian language and consists of introduction, 4 chapters, general conclusions and bibliography (208 references). The content of the thesis is exposed on 132 pages of basic text, contains 81 figures and 2 tables. The obtained results were published in 17 scientific papers, including 8 articles in international journals, 2 articles in national journals and 7 publications at national and international conferences.

Field of study: Nanotechnologies and new multifunctional nanomaterials.

Aim of the work: Elaboration of technological conditions for fabrication of GaN based 2D and 3D nano- and microarchitectures for applications in electronics, photonics and nanomedicine.

Objectives: Determination of technological conditions for fabrication of free-standing GaN ultrathin nanomembranes and fabrication of sensors, electronic and photonic devices. Identification of technological conditions for the spatial nanostructuring of GaN thin layers grown by MOCVD method and of GaN substrates grown by HVPE method for the fabrication of ordered 3D structures. Evaluation of the impact of semiconductor material nanoparticles incubated with living endothelial cells. The biocompatibility study on nanoparticles in dependence of chemical composition, concentration or their state. Identification of technological conditions which permit to avoid the aggregation effect of GaN nanoparticles in liquid medium.

Novelty and scientific originality: The development of electronic and photonic devices based on GaN nanomembranes fabricated using the Surface Charge Lithography technique. GaN crystal growth model and the nonuniform process of incorporation and distribution of impurities during the growth process is proposed and demonstrated.

The solved scientific problem: Determination of technological conditions for fabrication of GaN ultrathin nanomembranes for using in practical applications such as memristors, photonic crystals and biomedical applications. The nanoparticle agglomeration problem was solved using direct HVPE growth process of GaN nanocrystals on a substrate with spatial architecture. The biocompatibility of GaN nanoparticles with endothelial cells was demonstrated.

Theoretical significance and practical value of the work: The practical importance of the work reside in the elaborated applications, such as memristor device based on networks of GaN nanomembranes, also photonic crystals fabricated on nanoperforated GaN membranes. In this work it is proposed a model of incorporation and nonuniform distribution of the impurities during the growth process of GaN substrates, which model was verified using wet nanostructuring methods. Direct growth of GaN microcrystals on aerographite spatial network is important for fabrication of relatively high quantities of independent nanoparticles. The hydride structure based on Aerographite and GaN is mechanically stable, elastic and biocompatible. The interaction of semiconductor material nanoparticles and living endothelial cells demonstrate the biocompatibility of GaN nanoparticles. The nanoparticle uptake by the endothelial cells is important for the development of biomedical applications which imply electrical stimulation of living tissue or cells guiding in the liquid environments. These results are important fot the tissue engineering field in particular for the development of directed cell based therapy and remote electrical stimulation.

Implementation of scientific results: According to the obtained results, a patent was published in the Republic of Moldova.