Browsing by Author "Prilepov, Vladimir"

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DIFUZIA AG SUB ACȚIUNEA RAZELOR X ÎN STRUCTURILE CU STRATURI SUBȚIRI AS2S3 DOPATE CU FE
(CEP USM, 2022-11-10) Nasedchina, Nadejda; Prilepov, Vladimir; Sandu, Mădălina; Chiriţa, Arcadii
DIFUZIA Cu ÎN STRUCTURILE CU STRATURI SUBȚIRI (AS2S3)0,99 (BI2SE3)0,01 SUB ACȚIUNEA RADIAȚIILOR VIZIBILE ȘI RAZELOR X
(CEP USM, 2022-11-10) Prilepov, Vladimir; Nasedchina, Nadejda; Maistruc, Irina; Chiriţa, Arcadii
EFFECT OF OPTICAL COATING IN THE THIN-FILM SYSTEM OF CHALCOGENIDE GLASSY SEMICONDUCTOR-DIELECTRIC WHEN RECORDING THE HOLOGRAPHIC OPTICAL INFORMATION
(2015) Chirita, Arcady; Prilepov, Vladimir; Popescu, Mihai; Andries, Ion; Caraman, Mihail; Jidcov, Iurie
In this paper we show that the possibility of obtaining the high values of efficiency of relief-phase holographic gratings formed in the photo-thermoplastic recording process holds not only due to the non-sinusoidal profile form, but also due to the effect of optical coating that appears in the two-layer system of photo-semiconductor – deformed thermoplastic. Analyzed are the conditions, under which takes place the antireflection optical coating, reducing unwanted reflections from surfaces and thereby enhancing efficiency. It is shown that by careful choice of the thicknesses and refractive indices of the layers materials the efficiency of holographic gratings can be improved by 2-5 %.
MORPHOLOGY AND LUMINESCENCE PROPERTIES OF ZnO LAYERS PRODUCED BY MAGNETRON SPATTERING
(Technical University of Moldova, 2011-07-07) Rusu, Emil; Ghițu, Irina; Prilepov, Vladimir; Zamalai, Victor; Ursachi, Veaceslav
We show that the morphology and the luminescence properties of ZnO layers produced by magnetron sputtering can be controlled by technological parameters of sputtering, particularly by the ratio of argon to oxygen gases in the gas flow during the growth process. Smooth and flat layers were produced with a high Ar/O ratio, while porous layers with various morphologies were obtained with a low Ar/O ratio. The layers produced with O/Ar ration equal to 10 exhibit extremely high near-bandgap luminescence intensity even higher in comparison with bulk ZnO single crystals. The free carrier density estimated from the analysis of photoluminescence spectra is also very high in these samples suggesting that these technological conditions promote both optical and electrical activation of the doping Al impurity. The samples grown with high Ar/O ratios exhibit strong visible emission which is controlled by the technological conditions.
SEMICONDUCTORI CALCOGENICI STICLOȘI PE BAZĂ DE As - Se - S DOPAȚI CU STANIU PENTRU ÎNREGISTRAREA INFORMAȚIEI OPTICE
(CEP USM, 2020) Prilepov, Vladimir; Nasedchina, Nadejda; Spoială, Dorin; Matei, Leonid; Chirița, Arcadii
Au fost cercetate proprietăţile optice şi fotoelectrice ale straturilor subţiri pe bază de semiconductori calcogenici sticloşidin sistemul arsen -seleniu-sulf dopate cu staniu.
STRUCTURI FOTOSENSIBILE PE BAZĂ DE SEMICONDUCTORI CALCOGENICI STICLOŞI DIN SISTEMUL As-Se-S PENTRU ÎNREGISTRAREA INFORMAŢIEI OPTICE
(CEP USM, 2019) Prilepov, Vladimir; Nasedchina, Nadejda; Spoială, Dorin; Chiriţa, Arcadii
A fost elaborată tehnologia de depunere în vid a straturilor subţiri din sistemul As-Se -S într-un câmp electrostatic de tensiune înaltă. Experimental este arătatcă straturile subţiri de semiconductori calcogenici sticloşi obţinute prin metoda evaporării termice în vid în prezenţa câmpului electrostatic de intensitate înaltă au o eficacitate difracţională de ordinul +1 sporită, în comparaţie cu cele obţinute în absenţa câmpului.
STUDIES OF VANADIUM AND VANADIUM OXIDE BASED NANOCOMPOSITE STRUCTURES
(2017) Prilepov, Vladimir; Gashin, Peter A.; Popescu, Mihai; Zalamai, Victor; Spoiala, Dorin; Ketrush, Petru; Nasedchina, Nadejda
The results of the surface morphology studies as well as optical and electrical properties of nano-dimensional vanadium oxide composite structures deposited on various substrates- silica, glass substrates covered by conducting layer of SnO2, pure pyroceramics plates and the same covered by Al2O3, SiO2, Ta2O5 layers are presented. According to Raman spectroscopy results the thin film structure obtained on quartz corresponds to the -V2O5 orthorhombic phase. In contrast with this the Raman spectra of V2O5 films obtained on pyroceramics substrates, passivated by Al2O3, Ta2O5, SiO2 oxides, do not appear clearly marked narrow lines which indicate their amorphous character. The investigation of the optical properties of the fabricated layers in the spectral range of 200-1000 nm had revealed the presence of both allowed direct and indirect electron transitions. In the frequency range of 103-107 Hz the real Z' and imaginary Z'' part of the total impedance of pyroceramics/Al2O3/Al/V2O5/Al structure were studied. The applied direct bias leads to a considerable Z', as well as Z'' decrease. The analysis of the obtained dependencies is carried out by using the method of equivalent circuits.