Browsing by Author "Ghimpu, Lidia"

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Celule solare bazate pe filme subțiri CDTE:MN
(Editura USM, 2024) Suman, Victor; Potlog, Tamara; Morari, Vadim; Ghimpu, Lidia; Enăchescu, Marius
Heterostructures based on CdS/CdMnTe are being studied due to their semiconducting properties evidenced with a potential use in photovoltaics and their indispensability. Thin film solar cells generate the development of new practical and cost-effective alternative energy sources. The CdMnTe material is used together with CdTe as an absorber top layer in photovoltaic cells. Thus, HJ based on CdS/Cd MnTe as an alternative of cadmium telluride has been studied. In this study, the physical properties were studied, which demonstrate a cubic zinc blende structure and polycrystalline nature of CdMnTe layers. SEM micrographs of CdMnTe thin films demonstrate a homogeneity of the grains with a size between 3-5 μm, the thickness of the layers ranging between 5-6 μm. Examination of the physical properties of the CdS/CdMnTe solar cells revealed a conversion efficiency of 10.29 % with a filling factor of 61.63.
COPPER-RELATED DEFECTS IN ZnTe THIN FILMS GROWN BY THE CLOSE SPACE SUBLIMATION METHOD
(Academia de Ştiinţe a Moldovei, 2022) Lungu, Ion; Ghimpu, Lidia; Untila, Dumitru; Potlog, Tamara
Low-temperature photoluminescence (PL) is used to study defects evolution via immersion technique and annealing in vacuum of ZnTe thin films. In this paper we studied how copper doping from solutions of different molar concentrations affects PL of ZnTe thin films grown by close space sublimation (CSS) method. Undoped ZnTe thin films showed PL emission in the (520-680) nm wavelength region. The incorporation of copper in ZnTe produce a number of broad emission bands that correspond to an electron transition from the conduction band to spin-orbit states of the localized level of Cu2+ ions. All the studied samples had variable concentrations of oxygen and the possibility of the formation of auxiliary oxides is discussed.
PHOTOVOLTAIC MINIMODULE BASED ON CdTe
(2006) Potlog, Tamara; Ghimpu, Lidia; Balan, Ion
CdS/CdTe solar cells were fabricated without antireflection coatings by successive growth without intermediate processing from the close space sublimation of CdS and CdTe thin layers on conductive and transparent SnO2/glass substrates. At 300 K and 100 mW/cm2the following best photoelectric parameters were obtained: Isc= (18-19)mA/cm2 and Voc=(0,80-0,82)V. The conversion efficiency is around 10%. The quantum efficiency (QE) in the 510 nm and 845 nm range of wavelengths is on the order of 80-85%. The minimodule fabricated on the basis of the CdTe cells shows power of 0.45 W, corresponding to a voltage of 3 V, and current of 150 mA.
STUDY OF THE EFFECT OF HEAT TREATMENT ON OPTICAL AND ELECTRICAL PARAMETERS OF CuO FILMS
(2024) Suman, Victor; Lungu, Igor; Potlog, Tamara; Ghimpu, Lidia
SYNTHESIS AND ELECTROPHYSICAL PROPERTIES OF CdS/ZnTe HETEROJUNCTIONS
(Academia de Ştiinţe a Moldovei, 2022) Lungu, Ion; Gagara, Lyudmila; Ghimpu, Lidia; Potlog, Tamara
In this paper results of studying CdS/ZnTe heterostructures synthesized by the quasi- closed space sublimation method on glass substrates coated with an ITO layer are described. The electrical and photoelectric properties of the structures are studied using current–voltage and capacitance–voltage characteristics in a temperature range of 30–100 °C. Analysis of the experimental data shows that the main specific feature of CdS/ZnTe structures is the formation of a high-resistance transition layer, which affects the separation of carriers at the barrier contact. The current carrier concentration in the space charge region, which is determined from the capacitance–voltage characteristics, is 1  1015 cm3; this fact suggests that one of the contacting materials—ZnTe—exhibits a high resistivity. Measurements of current–voltage characteristics in the solar cell mode give the following photoelectric parameters: open circuit voltage (UOC = 0.53 V, JSC = 27–30 A/cm2, and FF = 0.25.