| 101. |
- Persson, Karl-Magnus, et al.
(författare)
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Cross-Point Arrays with Low-Power ITO-HfO2 Resistive Memory Cells Integrated on Vertical III-V Nanowires
- 2020
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Ingår i: Advanced Electronic Materials. - : Wiley. - 2199-160X. ; 6:6
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Tidskriftsartikel (refereegranskat)abstract
- Vertical nanowires with cointegrated metal-oxide-semiconductor field-effect-transistor (MOSFET) selectors and nonvolatile resistive random access memory (RRAM) cells represent a promising candidate for fast, energy-efficient, cross-point memory cells. This paper explores indium-tin-oxide-hafnium-dioxide RRAM cells integrated onto arrays of indium-arsenide (InAs) vertical nanowires with a resulting area of 0.06 µm2 per cell. For low current operation, an improved switching uniformity over the intrinsic self-compliant behavior is demonstrated when using an external InAs nanowire MOSFET selector in series. The memory cells show consistent switching voltages below ±1 V and a switching cycle endurance of 106 is demonstrated. The developed fabrication scheme is fully compatible with low-ON-resistance vertical III-V nanowire MOSFET selectors, where operational compatibility with the initial high-field filament forming is established. Due to the small footprint of a vertical implementation, high density integration is achievable, and with a measured programming energy for 50 ns pulses at 0.49 pJ, the technology promises fast and ultralow power cross-point memory arrays.
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| 102. |
- Persson, Karl-Magnus, et al.
(författare)
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Extrinsic and Intrinsic Performance of Vertical InAs Nanowire MOSFETs on Si Substrates
- 2013
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Ingår i: IEEE Transactions on Electron Devices. - 0018-9383. ; 60:9, s. 2761-2767
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents DC and RF characterization as well as modeling of vertical InAs nanowire MOSFETs with LG = 200 nm and Al2O3/HfO2 high-κ dielectric. Measurements at VDS = 0.5 V show that high transconductance (gm = 1.37 mS/μm), high drive current (IDS = 1.34 mA/μm), and low on-resistance (RON = 287 Ωμm) can be realized using vertical InAs nanowires on Si substrates. By measuring the 1/f-noise, the gate area normalized gate voltage noise spectral density, SVG·LG·WG, is determined to be lowered one order of magnitude compared to similar devices with a high-κ film consisting of HfO2 only. Additionally, with a virtual source model we are able to determine the intrinsic transport properties. These devices (LG = 200 nm) show a high injection velocity (vinj = 1.7·107 cm/s) with a performance degradation for array FETs predominantly due to an increase in series resistance.
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| 103. |
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| 104. |
- Persson, Karl-magnus, et al.
(författare)
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Investigation of Reverse Filament Formation in ITO/HfO2-based RRAM
- 2019
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Ingår i: 2019 Device Research Conference (DRC). - 9781728121123 - 9781728121116 ; , s. 91-92
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- To overcome the large discrepancy in speed between computational devices and that of contemporary large capacity non-volatile memory (NVM) technologies, resistive random access memory (RRAM) technologies are seen as promising candidates, offering speed/energy improvements in several orders of magnitude while being 3D integration compatible [1]. Indium-Tin-Oxide (ITO) has several unique properties for RRAM operation, perhaps most prominently the self-compliance and an ultra-low switching voltage (±200 mV) [2]. We report on considerations for ITO electrical bottom electrode (BE) RRAM where we vary the ALD oxide deposition parameters in order to improve the reverse filament formation (RFF) occurring at large reset voltages. RFF is when the conducting filament is reformed. One of the key parameters of RRAM is the endurance, how many times it can switch before failure. The RFF is one of the limitations in the number of switches until a device reaches failure and it is thus of high importance to ensure a sufficient margin between the highest applied reset voltage and the RFF voltage not to compromise the endurance. We optimized the oxide to improve the RFF properties.
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| 105. |
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| 106. |
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| 107. |
- Silva, José P.B., et al.
(författare)
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Roadmap on ferroelectric hafnia- and zirconia-based materials and devices
- 2023
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Ingår i: APL Materials. - 2166-532X. ; 11:8
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Tidskriftsartikel (refereegranskat)abstract
- Ferroelectric hafnium and zirconium oxides have undergone rapid scientific development over the last decade, pushing them to the forefront of ultralow-power electronic systems. Maximizing the potential application in memory devices or supercapacitors of these materials requires a combined effort by the scientific community to address technical limitations, which still hinder their application. Besides their favorable intrinsic material properties, HfO2-ZrO2 materials face challenges regarding their endurance, retention, wake-up effect, and high switching voltages. In this Roadmap, we intend to combine the expertise of chemistry, physics, material, and device engineers from leading experts in the ferroelectrics research community to set the direction of travel for these binary ferroelectric oxides. Here, we present a comprehensive overview of the current state of the art and offer readers an informed perspective of where this field is heading, what challenges need to be addressed, and possible applications and prospects for further development.
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| 108. |
- Staaf, Johan, et al.
(författare)
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Normalization of Illumina Infinium whole-genome SNP data improves copy number estimates and allelic intensity ratios
- 2008
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Ingår i: BMC Bioinformatics. - : Springer Science and Business Media LLC. - 1471-2105. ; 9, s. 409-
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Illumina Infinium whole genome genotyping (WGG) arrays are increasingly being applied in cancer genomics to study gene copy number alterations and allele-specific aberrations such as loss-of-heterozygosity (LOH). Methods developed for normalization of WGG arrays have mostly focused on diploid, normal samples. However, for cancer samples genomic aberrations may confound normalization and data interpretation. Therefore, we examined the effects of the conventionally used normalization method for Illumina Infinium arrays when applied to cancer samples. RESULTS: We demonstrate an asymmetry in the detection of the two alleles for each SNP, which deleteriously influences both allelic proportions and copy number estimates. The asymmetry is caused by a remaining bias between the two dyes used in the Infinium II assay after using the normalization method in Illumina's proprietary software (BeadStudio). We propose a quantile normalization strategy for correction of this dye bias. We tested the normalization strategy using 535 individual hybridizations from 10 data sets from the analysis of cancer genomes and normal blood samples generated on Illumina Infinium II 300 k version 1 and 2, 370 k and 550 k BeadChips. We show that the proposed normalization strategy successfully removes asymmetry in estimates of both allelic proportions and copy numbers. Additionally, the normalization strategy reduces the technical variation for copy number estimates while retaining the response to copy number alterations. CONCLUSION: The proposed normalization strategy represents a valuable tool that improves the quality of data obtained from Illumina Infinium arrays, in particular when used for LOH and copy number variation studies.
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| 109. |
- Staaf, Johan, et al.
(författare)
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Segmentation-based detection of allelic imbalance and loss-of-heterozygosity in cancer cells using whole genome SNP arrays
- 2008
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Ingår i: Genome Biology. - : Springer Science and Business Media LLC. - 1474-7596 .- 1465-6906 .- 1465-6914. ; 9:9
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Tidskriftsartikel (refereegranskat)abstract
- We present a strategy for detection of loss-of-heterozygosity and allelic imbalance in cancer cells from whole genome single nucleotide polymorphism genotyping data. Using a dilution series of a tumor cell line mixed with its paired normal cell line and data generated on Affymetrix and Illumina platforms, including paired tumor-normal samples and tumors characterized by fluorescent in situ hybridization, we demonstrate a high sensitivity and specificity of the strategy for detecting both minute and gross allelic imbalances in heterogeneous tumor samples.
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| 110. |
- Sulinskas, Karolis, et al.
(författare)
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Advantage of Binary Stochastic synapses for hardware Spiking Neural Networks with realistic memristors
- 2022
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Ingår i: Neuromorphic Computing and Engineering. - 2634-4386. ; 2
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Tidskriftsartikel (refereegranskat)abstract
- Hardware implementing spiking neural networks (SNNs) has the potential to provide transformative gains in energy efficiency and throughput for energy-restricted machine-learning tasks. This is enabled by large arrays of memristive synapse devices that can be realized by various emerging memory technologies. But in practice, the performance of such hardware is limited by non-ideal features of the memristor devices such as nonlinear and asymmetric state updates, limited bit-resolution, limited cycling endurance and device noise. Here we investigate how stochastic switching in binary synapses can provide advantages compared with realistic analog memristors when using unsupervised training of SNNs via spike timing-dependent plasticity. We find that the performance of binary stochastic SNNs is similar to or even better than analog deterministic SNNs when one considers memristors with realistic bit-resolution as well in situations with considerable cycle-to-cycle noise. Furthermore, binary stochastic SNNs require many fewer weight updates to train, leading to superior utilization of the limited endurance in realistic memristive devices.
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