Browsing by Author "Zaidan A."

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    EXPLORING THE STRUCTURAL AND ELECTRONIC CHARACTERISTICS OF AMORPHOUS Ge – Te - In MATERIAL THROUGH AB INITIO METHODS
    (2024-01-01) Zaidan A.; Ivanova V.; Petkov P.; Bancheva-Koleva P.
    This study employs density functional theory (DFT) and molecular dynamics to meticulously investigate the structural and electronic properties of ternary chalcogenide compounds, specifically (GeTe4)1-x Inx, and (GeTe5)1-x Inx across a range of compositions ( x = 0, 5, 10, 15, 20 at %). Utilizing the local density approximation within the framework of first-principles calculations, we comprehensively analyze the pair correlation function, static structural factor, electronic density of states, and electronic band gap energy. Our results reveal a notable decrease in the energy band gap of Germanium-Tellurium with the incorporation of Indium atoms. The structural changes observed in the Ge-Te matrix with Indium doping, as evidenced by the changes in the pair correlation function and static structure factor, are consistent with and supportive of the observed decrease in the band gap energy. This phenomenon is primarily attributed to the significant contribution of Indium atoms to the conduction band edge, offering new insights into the material’s electronic behaviour.
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    Optical properties of chalcogenide Ge-Te-In thin films
    (2012-01-01) Zaidan A.; Ivanova V.; Petkov P.
    Thin films of the chalcogenide (GeTe4)1-xIn x with various compositions (x 0, 5, 10, 15, 20 at %) were deposited under vacuum on glass substrates by thermal evaporation. The optical transmission and reflection spectra of the films at normal incidence were investigated in the spectral range from 800 to 2600 nm. Using the transmission spectra, the optical constants (refractive index (n) and extinction coefficient (k)) were calculated based on Swanepoel's method. The optical band gap (E gopt) was also estimated using Tauc's extrapolation procedure. © Published under licence by IOP Publishing Ltd.
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    Physical Vapor Deposition of Indium-Doped GeTe: Analyzing the Evaporation Process and Kinetics
    (2024-08-01) Zaidan A.; Ivanova V.; Petkov P.
    Chalcogenide glasses have broad applications in the mid-infrared optoelectronics field and as phase-change materials (PCMs) due to their unique properties. Chalcogenide glasses can have crystalline and amorphous phases, making them suitable as PCMs for reversible optical or electrical recording. This study provides an in-depth analysis of the evaporation kinetics of indium-doped chalcogenides, GeTe4 and GeTe5, using the physical vapor deposition technique on glass substrates. Our approach involved a detailed examination of the evaporation process under controlled temperature conditions, allowing precise measurement of rate changes and energy dynamics. This study revealed a significant and exponential increase in the evaporation rate of GeTe4 and GeTe5 with the introduction of indium, which was particularly noticeable at higher temperatures. This increase in evaporation rate with indium doping suggests a more complex interplay of materials at the molecular level than previously understood. Furthermore, our findings indicate that the addition of indium affects the evaporation rate and elevates the energy requirements for the evaporation process, providing new insights into the thermal dynamics of these materials. This study’s outcomes contribute significantly to understanding deposition processes, paving the way for optimized manufacturing techniques that could lead to more efficient and higher-performing optoelectronic devices and memory storage solutions.