Facultatea de Fizică şi Inginerie / Faculty of Physics and Engineering
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Item About the edge luminescence of cadmium sulphide thin layers grown on molybdenum [Articol](Institute of Electrical and Electronics Engineers, 1995-11-11) Raevschi, Simion; Gorceac, Leonid; Coval, Andrei; Chetruș, PetruCdS layers on to molybdenum were synthesized from separate elements in an open flowing hydrogen set. The surface micromorphology and some electrical and photoluminescent properties were investigated. The nature of layers edge photoluminescence peaks are discussed in the frames of the excitated exciton model.Item CdS nanometric layers grown on SnO2 coated glass substrates for photovoltaic devices [Articol](2012) Botnariuc, Vasile; Gorceac, Leonid; Coval, Andrei; Chetruș, Petru; Cinic, Boris; Raevschii, Simion; Micli, ValdecCdS layer thickness decreases at high substrate temperatures due to the fact that a part of CdCl2/(NH2)2 CS aqueous solution evaporates without reaching the substrate surface. CdS layers deposited at the substrate temperature from 250oC to 450oC are growing with a deficit of sulfur. CdS layers with better stoichiometry were grown in the conditions when in the solutions, used for CdS layers growing, there is an excess of thiourea (CdCl2/ TU =1:2). The high charge carrier concentration of 1020cm-3 in CdS layers grown on glass substrates coated with SnO2 layer is related to Sn doping of the layers from SnO2 layer.Item Stanat de cadmiu obţinut prin metoda pulverizării [Articol](CEP USM, 2013-09-26) Botnariuc, Vasile; Gorceac, Leonid; Coval, Andrei; Inculeţ, Ion; Chetruş, Petru; Raevschi, SimionItem Proprietăţi electrofizice ale straturilor de CdS obţinute prin metoda pulverizării cu tratare termică în hidrogen [Articol](CEP USM, 2012) Botnariuc, Vasile; Gorceac, Leonid; Coval, Andrei; Cinic, Boris; Chetruș, Petru; Raevschi, Semion; Banu, SimionPrin metoda pulverizării chimice au fost crescute straturi de CdS din soluţii apoase de CdCl2/(NH2)2 CS cu molaritatea de 0,1 M în intervalul de temperaturi (250...450)°C. Straturile au fost tratate termic în flux de hidrogen timp de 20 min la temperaturile de 350 şi 450°C. Au fost cercetate proprietăţile electrofizice şi fotoluminescenţa acestor straturi. În straturile depuse la 450°C cu mărirea temperaturii de tratare până la 450°C se observă o uşoară micşorare a concentraţiei purtătorilor de sarcină. Spectrul fotoluminescenţei prezintă o fâşie largă în intervalul de energii 1,6...2,6 eV. Se observă un vârf al fotoluminescenţei cu energia de 1,95 eV, care se deplasează cu mărirea temperaturii de creştere a straturilor de CdS şi atinge valoarea de 2,5 eV pentru straturile crescute la temperatura de 450°C.Item Straturi CdS crescute pe suporturi de sticlă prin metoda pulverizării [Articol](CEP USM, 2012) Botnariuc, Vasile; Gorceac, Leonid; Coval, Andrei; Chetruș, Petru; Cinic, Boris; Raevschi, Simion; Micli, ValdecCdS layers were grown from aqueous solutions of cadmium chlorine (CdCl2) and thyourine (NH2)2 CS with the molarity of 0,1 M by pulverization method in the temperature range of (250...450)°C. CdS layers were grown on glass substrates covered with a previously deposited SnO2 layer. The deposited CdS layers morphology, atomic weight and composition were studied biasing a sunning electron microscope (SEM). The morphology, atomic weight and composition of the deposited CdS layers considerably changes with the increase of the deposition temperature. The charge carriers’ concentration and their mobility in CdS layers deposited at different temperatures were measured and estimated.Item Straturi subţiri de CdS depuse din soluţii lichide (baie chimică) [Articol](CEP USM, 2011) Botnariuc, Vasilii; Gorceac, Leonid; Coval, Andrei; Raevschi, Simion; Micli, Valdec; Cinic, BorisThin layers of CdS were deposited on InP (100) substrates with a (3...5) arc degrees misorientation relative to (110) using water solutions of CdSO4, (NH4)2SO4, NH4OH, NH4Cl and CS(NH2)2 for synthesis. The morphology, atomic composition, photoluminescence and electrical properties of the deposited layers were investigated. The morphology of the CdS layers is characterized by a granular structure that is not changing under thermic treatment. A band in the energy interval (1,55 – 3,1) eV at 77 K with the maximum at 2,282 eV is observed in the photoluminescence spectra of the thin layers. Under thermic treatment from 200°C to 500°C in hydrogen the concentration of charge carriers is increasing from 2⋅1017 cm-3 to 2⋅1018 cm-3.Item Cercetarea celulelor solare cu heterojoncţiunea nCdS-pInP [Articol](CEP USM, 2009) Gorceac, Leonid; Botnariuc, Vasile; Raevschi, Simion; Coval, Andrei; Chitoroagă, AndreiPhotoelectrical dependencies of nCdS-pInP solar cells, as a function of electro physical parameters, crystallographic orientation of InP substrate and of the deposition duration of the nCdS epitaxial for layer are presented. It was established that the maximum value of the efficiency of solar energy into electrical one is obtained for the holes concentration in the substrate of 2·1016 cm-3, crystallographic orientation (100) and layer growth duration of 25 min. The hetero structure parameters influencing the named dependencies are determined.Item Obţinerea structurilor n+SnO2/nSi şi cercetarea proprietăţilor acestora [Articol](CEP USM, 2007) Bobeico, Eugenia; Bruc, Leonid; Caraman, Mihail; Coval, Andrei; Fedorov, Vladimir; Simaşchevici, Alexei; Şerban, Dormidont; Usatîi, IurieBy the method of pyrolitic spraying spirit solutions of chlorides of tin and antimony transparent (transmission ~ 85%) and conductive (σ ~ 102 Ohm-1cm-1) layers of SnO2:Sb were obtained. By using these layers izotype SIS structures In/n+SnO2 :Sb/SiO2/nSi/Cu are produced. Their electrophysical properties are studied. The energy diagram of heterostructure n+SnO2:Sb/nSi is constructed and the mechanism of current transition is determined.Item Parametrii celulelor solare nITO/pInP obţinute prin metoda pulverizării pirolitice în dependenţă de tratarea lor termică în hidrogen [Articol](CEP USM, 2007) Simaşchevici, Alexei; Şerban, Dormidont; Gorceac, Leonid; Bruk, Leonid; Coval, Andrei; Usatîi, Iurie; Fedorov, VladimirThe main objective of this communication is the investigation of the influence of thermal treatment in H2on the parameters of In/nITO/P2O5/pInP/Ag:Zn solar cells obtained by ITO layers pyrolithic pulverization. The ITO/pInP heterostructures obtaining take place at the temperature of 450ºC. The photoelectric parameters of the solar cell received on InP wafers with concentration p = 3·1017cm-3after the thermal treatment are Voc=0.626 V, Isc = 22.72 mA/cm2, FF = 71%, Eff =10.09%. As a result of these investigations it was shown that the thermal treatment of In/nITO/pInP/Ag:ZnSC in H2at 350oC during 10 min. leads to considerable improvement of their photoelectric parameters.Item Studiul proprietăţilor electrice şi fotovoltaice ale structurilor ITO-SI în baza siliciului multicristalin [Articol](CEP USM, 2009) Simaşchevici, Alexei; Şerban, Dormidont; Bruc, Leonid; Gorceac, Leonid; Coval, Andrei; Fedorov, Vladimir; Usatîi, IurieITO-polycrystalline p-type silicon structures with surface barriers are obtained by pyrolytical spraying of indium andtin chloride solutions and their electrical and photoelectrical properties are studied. The spectral sensibility range, current transport mechanisms and the parameters of the heterostructure under forward and reverse bias are determined. It isshown the possibility of using these heterojunctions in solar radiation conversion.