STRUCTURE, MORPHOLOGY AND HARDNESS OF A WAAM BUILT AL99.7 SPECIMEN

TITLE
STRUCTURE, MORPHOLOGY AND HARDNESS OF A WAAM BUILT AL99.7 SPECIMEN

AUTHOR(S)
Georgi Kotlarski, Maria Ormanova, Alexander Nikitin, Ralf Ossenbrink, Nikolay Doynov, Stefan Valkov, Vesselin Michailov

ABSTRACT
The present work discusses the possibility of wire arc additive manufacturing (WAAM) of pure aluminum specimens (Al99.7). The manufactured specimen’s structure was studied using X-ray diffraction (XRD) experiments. The morphology of the specimen at different stages of build-up was studied by examining pre-pared micrograph samples using an optical microscope. The resultant structure has a direct influence on the mechanical properties of the specimen, and for this reason the microhardness of the specimen was studied a well. The results of the present study were discussed regarding the change of the structure of the samples with the increase of the specimens’ height during the manufacturing process and its’ influence on the resultant microhardness.

DOI
www.doi.org/10.70456/PJKY7011

PAGES
317-321

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https://unitechsp.tugab.bg/images/2023/7-FH/s17_p149_v1.pdf

How to cite this article:
Georgi Kotlarski, Maria Ormanova, Alexander Nikitin, Ralf Ossenbrink, Nikolay Doynov, Stefan Valkov, Vesselin Michailov, STRUCTURE, MORPHOLOGY AND HARDNESS OF A WAAM BUILT AL99.7 SPECIMEN, UNITECH – SELECTED PAPERS - 2024, 317-321

EFFECT OF Ge-DOPING POSITION ON THE ELECTRONIC BAND STRUCTURE OF InP NANOWIRE

TITLE
PREDICTING WIND ENERGY PRODUCTION IN THE SHORT-TERM USING MACHINE LEARNING ALGORITHM

AUTHOR(S)
Sena Guler Ozkapi

ABSTRACT
In this study, the effect of Ge-doping on the electronic band structure of [111] oriented zinc-blende InP nanowires has been investigated using first-principles calculations based on density functional theory. The pure and H-passivated nanowires are formed to have a diameter of 1.5 nm. The doped InP nanowires are modeled by changing the position of the Ge atom. In place of In and P atoms, which are removed separately from different positions of the nanowire, Ge atoms are substituted. In order to determine the electronic properties, the band structures of all nanowires have been calculated. It is shown that the band structures obtained in the doping made by removing the In atom exhibit the character of an n-type semiconductor, while the band structures obtained in the doping made by removing the P atom form a p-type semiconductor.

DOI
www.doi.org/10.70456/FZDP3757

PAGES
312-316

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https://unitechsp.tugab.bg/images/2023/7-FH/s17_p106_v2.pdf

How to cite this article:
Sena Guler Ozkapi, EFFECT OF Ge-DOPING POSITION ON THE ELECTRONIC BAND STRUCTURE OF InP NANOWIRE, UNITECH – SELECTED PAPERS - 2024, 312-316

OPTICAL AND ELECTRONIC PROPERTIES OF COAXIAL SQUARE QUANTUM WELL WIRES AND FIELD EFFECTS

TITLE
OPTICAL AND ELECTRONIC PROPERTIES OF COAXIAL SQUARE QUANTUM WELL WIRES AND FIELD EFFECTS

AUTHOR(S)
Saban Aktas, Figen Karaca Boz, Sevket Erol Okan

ABSTRACT
The electronic and optical properties of the coaxial square quantum well wires were examined depending on their geometric parameters under external fields. Within the effective mass approximation, the finite difference and the variational methods were used in the calculations. The external fields such as electric, magnetic and laser fields affect the shape of the electronic wave function, and they also vary the energy states depending on their intensity. Thus, the blue shift in the total linear absorption coefficients can be provided as well as the photon energy.

DOI
www.doi.org/10.70456/GCVQ3795

PAGES
306-311

DOWNLOAD
https://unitechsp.tugab.bg/images/2023/7-FH/s17_p58_v1.pdf

How to cite this article:
Saban Aktas, Figen Karaca Boz, Sevket Erol Okan, OPTICAL AND ELECTRONIC PROPERTIES OF COAXIAL SQUARE QUANTUM WELL WIRES AND FIELD EFFECTS, UNITECH – SELECTED PAPERS - 2024, 306-311

THE PRE-WELL POTENTIAL AND CENTRAL WELL WİDTH EFFECTS ON A RESONANT TUNNELLING DIODE UNDER LASER FIELD

TITLE
THE PRE-WELL POTENTIAL AND CENTRAL WELL WİDTH EFFECTS ON A RESONANT TUNNELLING DIODE UNDER LASER FIELD

AUTHOR(S)
Hulya KES

ABSTRACT
A resonant tunneling diode, GaAs/In xGa 1-x As/Aly Ga 1-y As/GaAs/Al0.3Ga 0.7As/GaAs was studied under laser field. The effect of the pre-well potential In x Ga 1-x As on the current voltage characteristics was examined depending on the indium concentration. It has been observed that the current-voltage characteristic exhibits a critical value if the depth of the pre-well increased by increasing indium concentration. The electrons are accelerated for shallow pre-wells before that critical value and decelerated for deeper pre-wells than that of the critical value potential. In addition, the current is decreased increasing the width of the GaAs central well. The performance of the devices can be changed by applying a laser field when the geometric parameters are adjusted in resonant tunneling diodes.

DOI
www.doi.org/10.70456/CGRP4823

PAGES
301-305

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https://unitechsp.tugab.bg/images/2023/7-FH/s17_p57_v1.pdf

How to cite this article:
Hulya KES, Taşkın TEZ, THE PRE-WELL POTENTIAL AND CENTRAL WELL WİDTH EFFECTS ON A RESONANT TUNNELLING DIODE UNDER LASER FIELD, UNITECH – SELECTED PAPERS - 2024, 301-305

THE EFFECT OF TEMPERATURE ON THE SELF-POLARIZATION IN AN INFINITE GaAs/AlAs CYLINDRICAL QUANTUM WELL-WIRE

TITLE
THE EFFECT OF TEMPERATURE ON THE SELF-POLARIZATION IN AN INFINITE GaAs/AlAs CYLINDRICAL QUANTUM WELL-WIRE

AUTHOR(S)
Engin CİCEK

ABSTRACT
This work investigates the effects of temperature on self-polarization for different wire radii under an applied external magnetic field in an infinite GaAs/AlAs cylindrical quantum well-wire for the ground state. The variational method is used in the calculations by taking impurities in different positions from the centre to the edge of the wire. Self-polarization increases with increasing impurity atom distance from the centre, wire radius, and temperature. Moreover, as the magnetic field increases, self-polarization decreases. All calculations are in agreement with available data in the literature.

DOI
www.doi.org/10.70456/MCGO7649

PAGES
295-300

DOWNLOAD
https://unitechsp.tugab.bg/images/2023/7-FH/s17_p43_v2.pdf

How to cite this article:
Engin CİCEK, Taşkın TEZ, THE EFFECT OF TEMPERATURE ON THE SELF-POLARIZATION IN AN INFINITE GaAs/AlAs CYLINDRICAL QUANTUM WELL-WIRE, UNITECH – SELECTED PAPERS - 2024, 295-300