Yazar "Di Bartolomeo, Antonio" seçeneğine göre listele

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    High-Frequency Negative Capacitance in Graphene Quantum Dots/ Lanthanum(III) Hydroxide-based MIS Heterostructure
    (Elsevier, 2025) Anter, Aslıhan; Ulusoy, Murat; Polat, Barış; Yıldız, Mustafa; Di Bartolomeo, Antonio; Bi, Jinshun; Orhan, Elif
    Lanthanides have significant potential for electronic technologies based on graphene quantum dots (GQDs), as they have unique electronic configurations characterized by 4f electrons. In this context, lanthanum(III) hydroxide nanoparticles (La(OH)3NPs) are used as dopants for polyethyleneimine (PEI)-doped nitrogen (N)-doped graphene quantum dots(PEIGQDsN) in this study. Using a novel green method, the La(OH)3NPs-doped PEI GQDs N nanocomposites are prepared from La(NO)3 in a single step and exploited as an interlayer in a metal/interlayer/ semiconductor (MIS) heterojunction with Au and n-Si. Capacitance & conductance-voltage (C-V & G/omega-V) characteristics of the Au/La(OH)3NPs doped PEI GQDs N /n-Si MIS heterojunction have been investigated as a function of frequency in the wide 500 Hz to 3 MHz range from-3 V to 5 V, at 300 K. It has been observed that the structure is highly sensitive to the frequency. In particular, at high frequencies, above 1.5 MHz, the positive capacitance (PC) transforms into a negative capacitance (NC) in forward bias. In addition, impedance measurements at high frequencies were carried out after the measurements in the dark, while the surface of the structure was illuminated at 100 mW/cm2. At the frequencies of 2 MHz and 3 MHz, where inductive behavior was observed, the light refilled the depleted trap levels, catalyzing the transition from NC to PC in forward bias. These findings suggest that the capacitance and conductance of the heterojunction have a remarkable frequency sensitivity, particularly evident at higher frequencies. The outcomes of this study are poised to significantly influence the comprehension of carbon-lanthanides-based electronic technology, and enable the creation of new hybrid functional materials for use in electronic or optoelectronic applications.
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    Lanthanum(III)hydroxide Nanoparticles and Polyethyleneimine-Functionalized Graphene Quantum Dot Nanocomposites in Photosensitive Silicon Heterojunctions
    (Amer Chemical Soc, 2024) Anter, Aslıhan; Orhan, Elif; Ulusoy, Murat; Polat, Barış; Yıldız, Mustafa; Kumar, Arun; Di Bartolomeo, Antonio
    Lanthanides are largely used in optoelectronics as dopants to enhance the physical and optical properties of semiconducting devices. In this study, lanthanum(III)hydroxide nanoparticles (La(OH)(3)NPs) are used as a dopant of polyethylenimine (PEI)-functionalized nitrogen (N)-doped graphene quantum dots ( (PEI-N)GQDs). The La(OH)(3) NPs-doped (PEI-N)GQDs nanocomposites are prepared from La(NO)(3) in a single step by a green novel method and are characterized by Fourier-transform infrared spectroscopy (FT-IR), ultraviolet-visible spectroscopy (UV-vis), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). Deposited over an n-type Si wafer, the La(OH)(3) NPs-doped (PEI-N)GQDs nanocomposites form Schottky diodes. The I-V characteristics and the photoresponse of the diodes are investigated as a function of the illumination intensity in the range 0-110 mW cm(-2) and at room temperature. It is found that the rectification ratio and ideality factor of the diode decrease, while the Schottky barrier and series resistance increase with the enhancing illuminations. As a photodetector, the La(OH)(3) NPs-doped (PEI-N)GQDs/n-Si heterojunction exhibits an appreciable responsivity of 3.9 x 10(-3) AW(-1) under 22 mW cm(-2) at -0.3 V bias and a maximum detectivity of 8.7 x 10(8) Jones under 22 mW cm(-2) at -0.5 V. This study introduces the green synthesis and presents the structural, electrical, and optoelectronic properties of La(OH)(3) NPs-doped (PEI-N)GQDs, demonstrating that these nanocomposites can be promising for optoelectronic applications.
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    Tunable dielectric characteristics of the nanocomposite diode based on functionalized graphene quantum dots with and without gadolinium
    (Elsevier, 2024) Berktaş, Zeynep; Anter, Aslıhan; Dikicioğlu, Elanur; Ulusoy, Murat; Candan, Can; Yıldız, Mustafa; Di Bartolomeo, Antonio
    In this study, we have separately synthesized and characterized solutions of gadolinium (Gd)-free and Gd-doped polyethyleneimine (PEI)-functionalized graphene quantum dots (GQDs) due to the excellent properties of Gd, a rare earth element, in fluorescence and magnetic resonance imaging (MRI). The dielectric properties of Gd-free/ doped nanocomposite-based diodes have been compared using impedance spectroscopy (IS) in the frequency range from 1 kHz to 500 kHz and voltage range from -3 V to +5 V at 300 K. From our experimental results, the Gd-free diode was found to have a negative dielectric constant (e '). In contrast, the Gd-doped nanocomposite diode exhibited positive e '. The epsilon ' of the Gd-free diode is -80, while the e ' of the Gd-doped diode is 35 at 5 V for 1 kHz. The experimental results showed that the dielectric properties of both structures were strongly dependent on the applied voltage and frequency. The Gd doping in the interface has prevented the domination of loss mechanisms within the structure, eliminated negative dielectric at lower frequencies, and conferred a unique micro-capacitor characteristic to the structure. All these efforts will contribute to the development of functional carbon-based materials and the creation of new electronic devices and tunable dielectric properties.