Browsing by Author "Akkanaboina Mangababu"

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Effects of heavy ion irradiation on the electrical properties of HfTiOx-based MOS devices
(Taylor and Francis Ltd., 2025) R. Sai Prasad Goud; Sravani Machiboyina; G. Prashanth; Akkanaboina Mangababu; Kanaka Ravi Kumar; Bharatha Aparna; Banothu Saidulu; Saif Ahmad khan; S. V.S. Nageswara Rao; Anand Prakash Pathak
This manuscript presents our recent investigations on the effects of swift heavy ion irradiation on the electrical properties of Hafnium Titanium Oxide (HfTiOx)-based Metal Oxide Semiconductor (MOS) devices. Al/HfTiOx/Si MOS devices were irradiated with 120 MeV Ag9+ ions over a range of fluences (1 E 11–1 E 13 ions/cm2). A systematic study on defects generated by heavy ion irradiation on MOS devices has been analysed thoroughly by using current–voltage (I-V) and capacitance–voltage (C-V) measurements. The radiation damage on these devices is explained by examining the role of various conduction mechanisms observed in leakage currents before and after irradiation. Hence, this work will provide valuable insights regarding radiation damage in HfTiOx-based MOS devices in space and medical applications. © 2025 Informa UK Limited, trading as Taylor & Francis Group.
Effects of ion irradiation induced phase transformations and oxygen vacancies on the leakage current characteristics of HfO2 thin films deposited on GaAs
(Institute of Physics, 2025) K. Vinod Anil Kumar; Nimmala Arun; Akkanaboina Mangababu; Ambuj Mishra; Sunil C. Ojha; Anand Prakash Pathak; S. V.S. Nageswara Rao
We report on ion-induced phase transformations, defect dynamics related to oxygen vacancies and the resulting leakage current characteristics of RF sputtered HfO2 thin films grown on GaAs. A systematic growth of HfO2 grains and ion prompted phase transformations of HfO2 to crystalline phases such as monoclinic and tetragonal/orthorhombic (mixed phase) in otherwise amorphous HfO2 thin films have been observed after irradiation. At lower fluences, ion induced enhancement in the dielectric properties of HfO2 thin films resulted in a reduction in the leakage current, whereas ion prompted defect formation at higher fluences caused a systematic increase in the leakage current density. Further, the effects of Poole-Frenkel tunneling and Fowler-Nordheim tunneling on the leakage current have also been investigated. These mechanisms showed the existence of impurities in the as-grown films. Photoluminescence study suggests that the variation in the defect configuration related to O-vacancies and the slight shift in the peak positions due to swift heavy ion irradiation are responsible for the observed changes in electrical characteristics. This study offers worthwhile information for considering the effects of electronic excitation prompted defect annealing and defect creation on the performance of HfO2/GaAs based photonic and optoelectronic devices, particularly, when such devices are operated in a radiation harsh environment. © 2024 IOP Publishing Ltd. All rights, including for text and data mining, AI training, and similar technologies, are reserved.
Structural characterization of AlCuFe icosahedral quasicrystal nanoparticles synthesized using femtosecond laser ablation
(Springer, 2025) Bibek Kumar Singh; Dipanjan Banerjee; Akkanaboina Mangababu; Yagnesh Shadangi; Nilay Krishna Mukhopadhyay; Rajesh Rawat; Anand Prakash Pathak; Venugopal Rao Soma; Archana Tiwari; Ajay Tripathi
The AlCuFe icosahedral quasicrystal (IQC) targets prepared using two different methods- (1) vacuum induction melting followed by annealing, and (2) spray forming, have been subjected to femtosecond laser ablation in deionized water (DI water) for 54 min. High-resolution transmission electron microscopy (HRTEM) and selected area electron diffraction (SAED) pattern analysis of the synthesized nanoparticles (NPs) revealed the presence of IQC phases. NPs obtained from the induction-melted IQC target contained Al13Fe4 and β-Al(Fe,Cu) phases along with the IQC phase, reflecting the phase composition of the bulk target. In contrast, NPs from the spray-formed target exhibited only the IQC phase. Both samples also showed the presence of CuO and amorphous Al2O3. The ablated region of the target surface showed the formation of grooves and bumps. In addition, the formation of liquid vortices during the ablation process was ascertained by the presence of macropores in the ablated region of the target’s surface. I-V plots obtained from the ablated region and the non-ablated region of the target’s surface revealed an increase in the resistance post-ablation. This increase is attributed to the presence of defects and surface oxidation that incurred during the laser irradiation. © The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature 2024.
Thermally tunable dual channel toroidal metasurface on VO2 platform
(American Institute of Physics, 2025) S. N. Yogitha; Nityananda Acharyya; Abhishek Mishra; Akkanaboina Mangababu; Amit Kumar Verma; Dhanvir Singh Rana; Dibakar Roy Chowdhury
Active modulation of electromagnetic response in terahertz (THz) regime has gathered plenty of attention owing to its multifunctional applications. In this regard, metasurfaces integrated with VO2 as active material can create compelling pathways for actively controlling terahertz propagation. Hence, we have demonstrated a design of dual toroidal active metasurface by realizing plasmonic split-ring resonators on the VO2 thin film for dynamic and real-time control over THz wave propagation. These metasurfaces exhibit agile modulation of multiple resonances by exploiting insulator-to-metal transition (IMT) phenomena exhibited by VO2. For this purpose, sample temperature is varied from 26 to 110 °C. It is observed that at 110 °C, VO2 conductivity increased significantly resulting in a 46% peak amplitude modulation with respect to room temperature. Besides temperature induced tunability mediated by VO2 activated IMT, these metasurfaces manifest temperature tunable electric, magnetic, and toroidal modes which is further validated by rigorous multipole analysis. Hence, these outcomes provide a framework for implementing VO2 based temperature tunable THz metadevices for futuristic applications such as thermal sensors, modulators, terahertz switching, tunable absorbers, and photonic memory. © 2025 Author(s).