Browsing by Author "Simașchevici, Alexei"

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Silicon carbide nanolayers as a solar cell constituent [Articol]
(2015) Zakhvalinskii, Vasilii; Pilyk, Evghenii; Goncharov, Igor; Simașchevici, Alexei; Șerban, Dormidont; Bruc, Leonid; Curmei, Nicolai; Rusu, Marin
Thin films of predominantly amorphous n-type SiC were prepared by non-reactive magnetron sputtering in an Ar atmosphere. A previously synthesized SiC was used as a solid-state target. Deposition was carried out on a cold substrate of p-type Si (100) with a resistivity of 2 Vcm. The Raman spectrum shows a dominant band at 982 cm 1 , i.e., in the spectral region characteristic for SiC. It was found that the root mean square roughness varies from about 0.3 nm to 9.0 nm when the film thickness changes from about 2 nm to 56 nm, respectively. Transmission electron microscopy studies showed that SiC thin films consist predominantly of an amorphous phase with inclusions of very fine nanocrystallites. A heterostructure consisting of a p-type Si (100) and a layer of predominantly amorphous n-type SiC was fabricated and studied. The investigation of its electrical and photoelectric properties shows that the entire space charge region is located in Si. This is in addition confirmed by the spectral dependence of the p-Si/n-SiC photosensitivity. The barrier height at the p-Si/n-SiC interface estimated from dark I–V characteristics is of the order of 0.9–1.0 eV. Load I–V characteristics of p-Si/n-SiC-nanolayer solar cells demonstrate under standard AM1.5 illumination conditions a conversion efficiency of 7.22%.
Thin Films of Titanium and Tin Oxides and Semiconductor Structures on Their Basis Obtained by Pyrolytic Pulverization: Preparation, Characterization, and Corrosion Properties [Articol]
(2007) Bersirova, Oxana; Bruc, Leonid; Dicusar, Alexandr; Caraman, Mihail; Sidelinicova, Svetlana; Simașchevici, Alexei; Șerban, Dormidont; Iaponteva, Iu.
Peculiarities of obtaining of tin oxide and titanium oxide layers and semiconductor structures on their basis are described. The X-ray diffraction data show that the SnO2 and TiO 2 layers possess the tetragonal crystal structure (anatase modification for TiO2). The results of analysis of the elemental composition and impedance investigations of the fabricated structures in model chloride–sulfate solutions demonstrate that the oxide/SiO2/Si structures are obtained if Si substrates are used. In the case of InP substrates, the oxide layer at the interface is not detected and the corresponding structure is oxide/InP. The results of investigations of corro- sion show that a substantial shift of the corrosion potential to the anode region is observed in the case of depo- sition of SnO2 and TiO2 oxide layers on Si and InP crystals and fabrication of corresponding semiconductor structures. This demonstrates the possibility of the use of these materials in photoelectrochemical applications.