Browsing by Author "Rotaru, Corneliu"

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    DISPOZITIVE DIN FOSFURĂ DE INDIU BAZATE PE EFECTUL FOTOVOLTAIC
    (CEP USM, 2021) Botnariuc, Vasile; Gorceac, Leonid; Coval, Andrei; Vatavu, Sergiu; Cinic, Boris; Rotaru, Corneliu; Raevschi, Simion
    Homo- și heterojoncțiunile din p - InP și n - CdS au fost confecționate aplicând metoda epitaxiei din faza gazoasă în volum deschis, în sistem de cloruri, metoda HVPE (Hydride Vapour Phase Epitaxy) și tehnologia în volum cvasiînchis, în hidrogen. S-a stabilit că eficiența celulelor fotovoltaice pe bază de heterojoncțiuni n+CdS-p-p+InP cu suprafața fotoactivă de 3 cm2 și pe homojoncțiuni n+- p- p+InP (1 cm2) constituie 12% și,respectiv, 7,3% în condiții de iluminare standard, AM1 (1000 Wm-2). Eficiența cuantică externă maximală constituie 75-80% pentru heterojoncțiunea n+CdS - p- p+ InP și 70% pentru homojoncțiunea n+-p-p+InP în intervalul (600-900) nm al spectrului electromagnetic. Fotosensibilitatea absolută maximă de 0,51 A/W este caracteristică pentru heterojoncțiunea n+CdS - p- p+InP cu strat epitaxial intermediar(p = 6,51016 cm-3). Astfel de heterojoncțiuni pot fi utilizate pentru elaborarea fotodetectorilor în intervalul VIS.
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    EDUCAŢIE PENTRU DRONE : SUPORT DE CURS
    (CEP USM, 2019) Nedeoglo, Natalia; Rotaru, Corneliu; Sprincean, Veaceslav; Danici, Anton; Seinic, Valeriu; Vozian, Constantin; Cazan, Valeriu; Corcimari, Ion; Cebotaru, Eugenia
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    FOTODETECTOR PE HETEROJONCȚIUNE DIN FOSFURĂ DE INDIU
    (CEP USM, 2020) Gorceac, Leonid; Botnariuc, Vasile; Coval, Andrei; Vatavu, Sergiu; Cinic, Boris; Raevschi, Simion; Rotaru, Corneliu
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    THE INVESTIGATION OF TCO/CdS/CdTe HETEROJUNCTIONS BY C-U and C-f MEASUREMENTS: EXPERIMENT AND MODELING
    (IEEE, 2013) Rotaru, Corneliu; Vatavu, Sergiu; Fedorov, Vladimir; Gașin, Petru; Lux-Steiner, Martha; Ferekides, Chris; Rusu, Marin
    The paper presents the analysis of C-U and C-f data obtained in the 1 kHz-10 MHz range for CdS/CdTe heterojunctions prepared by CSS onto (ZnO:Al, ZnO:Al/i-ZnO)/Glass substrates. An attempt to model the physical properties of the heterojunctions is made. A small signal analysis has been carried out to establish the equivalent circuit of device. The unusual capacitance behavior of the ZnO based heterojunction is attributed to presence of the barrier at the back contact.
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    PARTICULARITĂȚI STRUCTURALE ALE FILMELOR ZnSnN2
    (CEP USM, 2024) Ghilețchii, Gheorghe; Narolschi, Igor; Rotaru, Corneliu; Rusu, Marin; Vatavu, Sergiu
    ZnSnN2 is composed of common non-toxic elements. It exhibits promising optoelectronic properties for application in photoelectric conversion and electromagnetic radiation detection devices. However, the available data on its physical properties are incomplete or contradictory. In this work, we prepare ZnSnN2 thin films and study in detail their structural properties as functi on of deposition conditions. DC magnetron sputtering was used because it allows the preparation of thin polycrystalline ZnSnN2 films on large areas and it can be easily upscaled. The films were prepared using targets of various atomic [Zn]/[Sn] ratios in nitrogen atmosphere at temperatures ranging from 30 to 300°C. Structural analysis, using Grazing Incidence X-ray Diffraction (GI XRD) and X-ray Reflectivity (XRR), revealed the formation of polycrystalline ZnSnN2 films with a wurtzite crystal structure. The obtained structural parameters were found to be influenced by the substrate temperature and elemental concentration in the target. These findings will be used for optimization of the manufacturing process for desired film characteristics.
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    PARTICULARITĂȚI STRUCTURALE ALE FORMĂRII NANOSTRATURILOR DE CdS PE SUBSTRATURI DE ZnO ȘI SnO2
    (CEP USM, 2024) Rotaru, Corneliu
    CdS is a material whose physical properties with optoelectronic applications are influen ced by the preparation technology, especially the type of substrate and its temperatures. CdS thin films were deposited by the CSS method on TCO (AZO, SnO2 )/Glass substrates, varying the substrate temperature between 280-460°C and keeping the evaporation temperature constant at 630°C. Grazing Incidence X-ray Diffraction (GI-XRD) and X-ray Reflectivity (XRR), were used for structural characterizations. The substrate temperature increase (CdS/ZnO:Al/Glass structu re) results in decrease of the microstrain values.
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    PROPRIETATILE ELECTRONICE A SUPRAFETEI STRATURILOR DE CdS DEPUSE PE SUPORTURI DE ZnO ȘI SnO2
    (CEP USM, 2024) Rotaru, Corneliu
    Electronic properties of the CdS thin films deposited by Close-Spaced Sublimation have been investigated by Kelvin Probe (KP) and Photoelectron Yield Spectroscopy (PYS). The Fermi level position changes between 180 meV and 320 meV below the conduction band minimum for the CdS/AZO heterojunction while the CdS thin films on SnO2 substrates show degeneration. An influence of the technology aspects on the energetic structure of the CdS nanolayer is shown.
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    RADIATIVE RECOMBINATION MECHANISMS IN CDTE THIN FILMS DEPOSITED BY ELEMENTAL VAPOR TRANSPORT
    (Elsevier, 2015) Collins, Shamara; Vatavu, Sergiu; Evani, Vamsi; Khan, Md; Bakhsh, Sara; Palekis, Vasilios; Rotaru, Corneliu; Ferekides, Chris
    A photoluminesence (PL) study of the radiative recombination mechanisms for CdTe films deposited under different Cd and Te overpressure by elemental vapor transport is presented. The experiment and analysis have been carried out in the temperature range of 12–130 K. The intensity of the PL laser excitation beam was varied by two orders of magnitude. It has been established that the bands in the 1.47–1.50 eV are determined by transitions involving shallow D and A states and the 1.36x–1.37x eV band is due to band to level transitions. Deep transitions at 1.042 eV and 1.129 eV are due to radiative transitions to levels determined by CdTe native defects.
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    STRATURI SUBȚIRI Ga2S3 PENTRU APLICAȚII ÎN DETECTORI DE RADIAȚII ELECTROMAGNETICE
    (CEP USM, 2022-11-10) Spoială, Dorin; Ghilețchii, Gheorghe; Vatavu, Elmira; Dmitroglo, Liliana; Şapoval, Oleg; Belenciuc, Alexandr; Rotaru, Corneliu; Narolschi, Igor; Vatavu, Sergiu
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    STRATURI SUBȚIRI SEMICONDUCTOARE PREPARATE ÎN SISTEME DE PULVERIZARE CU MAGNETRON (DC): TEORIE vs EXPERIMENT (I)
    (CEP USM, 2020) Narolschi, Igor; Cliucanov, Alexandr; Rotaru, Corneliu; Rusu, Marin; Vatavu, Sergiu
    Caracteristica curent-tensiune a sistemului de pulverizare cu magnetron(DC) depinde în formă pătratică de trei parametri,unul dintre care este egal cu potențialul de aprindere a descărcării gazului, pe când ceilalți doi parametri se determină experimental din caracteristica curent-tensiune pentru valori mici sau mari ale tensiunii aplicate sistemului.
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    STRUCTURA ȘI MORFOLOGIA STRATURILOR NANOMETRICE DE ZnSnN2 PREPARATE PRIN MAGNETRON SPUTTERING
    (CEP USM, 2022-11-10) Narolschi, Igor; Ghilețchii, Gheorghe; Cliucanov, Alexandr; Rotaru, Corneliu; Spoială, Dorin; Vatavu, Elmira; Şapoval, Oleg; Belenciuc, Alexandr; Dmitroglo, Liliana; Bercu, Elena; Rusu, Marin; Vatavu, Sergiu