Publications by authors named "Albena Paskaleva"

This study investigates the effects of negative bias temperature (NBT) stress and irradiation on the threshold voltage () of p-channel VDMOS transistors, focusing on degradation, recovery after each type of stress, and operational behavior under varying conditions. Shifts in (Δ) were analyzed under different stress orders, showing distinct influence mechanisms, including defects creation and their removal and electrochemical reactions. Recovery data after each type of stress indicated ongoing electrochemical processes, influencing subsequent stress responses.

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The physical properties of ZnO can be tuned efficiently and controllably by doping with the proper element. Doping of ZnO thin films with 3D transition metals that have unpaired electron spins (e.g.

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This study aimed to comprehensively understand the performance and degradation of both p- and n-channel vertical double diffused MOS (VDMOS) transistors under bias temperature stress. Conducted experimental investigations involved various stress conditions and annealing processes to analyze the impacts of BT stress on the formation of oxide trapped charge and interface traps, leading to threshold voltage shifts. Findings revealed meaningful threshold voltage shifts in both PMOS and NMOS devices due to stresses, and the subsequent annealing process was analyzed in detail.

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In this work, a novel approach is suggested to grow bilayer fibers by combining electrospinning and atomic layer deposition (ALD). Polyvinyl alcohol (PVA) fibers are obtained by electrospinning and subsequently covered with thin AlO deposited at a low temperature by ALD. To burn the PVA core, the fibrous structures are subjected to high-temperature annealing.

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The magneto-optical (MO) Kerr effects for ZnO and ZnO:Ni-doped nanolaminate structures prepared using atomic layer deposition (ALD) have been investigated. The chemical composition and corresponding structural and morphological properties were studied using XRD and XPS and compared for both nanostructures. The 2D array gradient maps of microscale variations of the Kerr angle polarization rotation were acquired by means of MO Kerr microscopy.

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The requirements for ever-increasing volumes of data storage have urged intensive studies to find feasible means to satisfy them. In the long run, new device concepts and technologies that overcome the limitations of traditional CMOS-based memory cells will be needed and adopted. In the meantime, there are still innovations within the current CMOS technology, which could be implemented to improve the data storage ability of memory cells-e.

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ZnO doped with transition metals (Co, Fe, or Ni) that have non-compensated electron spins attracts particular interest as it can induce various magnetic phenomena and behaviors. The advanced atomic layer deposition (ALD) technique makes it possible to obtain very thin layers of doped ZnO with controllable thicknesses and compositions that are compatible with the main microelectronic technologies, which further boosts the interest. The present study provides an extended analysis of the magneto-optical MO Kerr effect and the dielectric properties of (Co, Fe, or Ni)-doped ZnO films prepared by ALD.

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Flash memories are the preferred choice for data storage in portable gadgets. The charge trapping nonvolatile flash memories are the main contender to replace standard floating gate technology. In this work, we investigate metal/blocking oxide/high-k charge trapping layer/tunnel oxide/Si (MOHOS) structures from the viewpoint of their application as memory cells in charge trapping flash memories.

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High- dielectric stacks are regarded as a promising information storage media in the Charge Trapping Non-Volatile Memories, which are the most viable alternative to the standard floating gate memory technology. The implementation of high-k materials in real devices requires (among the other investigations) estimation of their radiation hardness. Here we report the effect of gamma radiation (Co source, doses of 10 and 10 kGy) on dielectric properties, memory windows, leakage currents and retention characteristics of nanolaminated HfO/AlO stacks obtained by atomic layer deposition and its relationship with post-deposition annealing in oxygen and nitrogen ambient.

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In this work dielectric and electrical properties of Al-doped HfO2 layers deposited by plasma-enhanced atomic layer deposition in dependence on the thickness and the added Al amount in the films have been investigated. Special attention is dedicated to C-V and I-V hysteresis analysis as a measure for trapping phenomena in the films. A detailed study of conduction mechanisms in dependence on the composition of the layers has also been performed.

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Article Synopsis
  • The study examines the topography and leakage current behaviors of TiO2 films created through atomic layer deposition on RuO2 electrodes, using either TiCl4 or Ti(O-i-C3H7)4 as precursors.
  • For both types of films, the leakage current is primarily concentrated in elevated grain areas rather than along the grain boundaries.
  • It was found that the TiCl4-based films exhibit a higher and more localized leakage current compared to those based on Ti(O-i-C3H7)4, with both films maintaining a similar physical thickness of about 20 nm.
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