TY - GEN A1 - Rodríguez-Calcerrada, Jesús A1 - Salomón, Roberto L. A1 - Gordaliza, Guillermo G. A1 - Miranda, José C. A1 - Garcia de la Riva, Enrique A1 - Gil, Luis T1 - Respiratory costs of producing and maintaining stem biomass in eight co-occurring tree species T2 - Tree Physiology Y1 - 2019 UR - https://academic.oup.com/treephys/article/39/11/1838/5519950 U6 - https://doi.org/10.1093/treephys/tpz069 SN - 1568-2544 VL - 39 IS - 11 SP - 1838 EP - 1854 ER - TY - GEN A1 - Ossorio, Óscar G. A1 - Vinuesa, Guillermo A1 - Garcia, Hector A1 - Sahelices, Benjamin A1 - Dueñas, Salvador A1 - Castán, Helena A1 - Pérez, Eduardo A1 - Mahadevaiah, Mamathamba Kalishettyhalli A1 - Wenger, Christian T1 - Performance Assessment of Amorphous HfO2-based RRAM Devices for Neuromorphic Applications T2 - ECS Transactions N2 - The use of thin layers of amorphous hafnium oxide has been shown to be suitable for the manufacture of Resistive Random-Access memories (RRAM). These memories are of great interest because of their simple structure and non-volatile character. They are particularly appealing as they are good candidates for substituting flash memories. In this work, the performance of the MIM structure that takes part of a 4 kbit memory array based on 1-transistor-1-resistance (1T1R) cells was studied in terms of control of intermediate states and cycle durability. DC and small signal experiments were carried out in order to fully characterize the devices, which presented excellent multilevel capabilities and resistive-switching behavior. KW - RRAM KW - resistive switching KW - HfO2 Y1 - 2021 U6 - https://doi.org/10.1149/10202.0029ecst SN - 1938-6737 SN - 1938-5862 VL - 102 IS - 2 SP - 29 EP - 35 ER - TY - GEN A1 - Martre, Pierre A1 - Dueri, Sibylle A1 - Guarin, Jose Rafael A1 - Ewert, Frank A1 - Webber, Heidi A1 - Calderini, Daniel A1 - Molero, Gemma A1 - Reynolds, Matthew A1 - Miralles, Daniel A1 - Garcia, Guillermo A1 - Brown, Hamish A1 - George, Mike A1 - Craigie, Rob A1 - Cohan, Jean‐Pierre A1 - Deswarte, Jean-Charles A1 - Slafer, Gustavo A. A1 - Giunta, Francesco A1 - Cammarano, Davide A1 - Ferrise, Roberto A1 - Gaiser, Thomas A1 - Gao, Yujing A1 - Hochman, Zvi A1 - Hoogenboom, Gerrit A1 - Hunt, Leslie A. A1 - Kersebaum, Kurt C. A1 - Nendel, Claas A1 - Padovan, Gloria A1 - Ruane, Alex C. A1 - Srivastava, Amit Kumar A1 - Stella, Tommaso A1 - Supit, Iwan A1 - Thorburn, Peter A1 - Wang, Enli A1 - Wolf, Joost A1 - Zhao, Chuang A1 - Zhao, Zhigan A1 - Asseng, Senthold T1 - Global needs for nitrogen fertilizer to improve wheat yield under climate change T2 - Nature Plants Y1 - 2024 U6 - https://doi.org/10.1038/s41477-024-01739-3 SN - 2055-0278 VL - 10 IS - 7 SP - 1081 EP - 1090 PB - Springer Science and Business Media LLC ER - TY - GEN A1 - Vinuesa, Guillermo A1 - Garcia, Hector A1 - Duenas, Salvador A1 - Castan, Helena A1 - Iñiguez de la Torre, Ignacio A1 - Gonzalez, Tomas A1 - Dorai Swamy Reddy, Keerthi A1 - Uhlmann, Max A1 - Wenger, Christian A1 - Perez, Eduardo T1 - Effect of the temperature on the performance and dynamic behavior of HfO2-Based Rram Devices T2 - ECS Meeting Abstracts N2 - Over the past decades, the demand for semiconductor memory devices has been steadily increasing, and is currently experiencing an unprecedented boost due to the development and expansion of artificial intelligence. Among emerging high-density non-volatile memories, resistive random-access memory (RRAM) is one of the best recourses for all kind of applications, such as neuromorphic computing or hardware security [1]. Although many materials have been evaluated for RRAM development, some of them with excellent results, HfO2 is one of the established materials in CMOS domain due to its compatibility with standard materials and processes [2]. The main goal of this work is to study the switching capability and stability of HfO2-based RRAMs, as well as to explore their ability in the field of analogue applications, by analyzing the evolution of the resistance states that allow multilevel control. Indeed, analogue operation is a key point for achieving electronic neural synapses in neuromorphic systems, with synaptic weight information encoded in the different resistance states. This research has been carried out over a wide temperature range, between 40 and 340 K, as we are interested in testing the extent to which performance is maintained or modified, with a view to designing neuromorphic circuits that are also suitable in the low-temperature realm. We aim to prove that these simple, fast, high integration density structures can also be used in circuits designed for specific applications, such as aerospace systems. The RRAM devices studied in this work are TiN/Ti/8 nm-HfO2/TiN metal-insulator-metal (MIM) capacitors. Dielectric layers were atomic layer deposited (ALD). It has been demonstrated that the Ti coat in the top electrode acts as a scavenger that absorbs oxygen atoms from the HfO2 layer, and facilitates the creation of conductive filaments of oxygen vacancies [3]. In fact, the oxygen reservoir capability of Ti is well known, as it is able to attract and release oxygen atoms from or to the HfO2 layer during the RRAM operation [4]. The clustering of vacancies extends through the entire thickness of the oxide and, after an electroformig step, it joins the upper and lower electrodes and the device reaches the low resistance state (LRS). By applying adequate electrical signals, the filaments can be partially dissolved, which brings the device into the high-resistance state (HRS), with lower current values. The set process brings the device to the LRS state, while the reset one brings it to the HRS. The dependence of electrical conductivity on external applied electrical excitation allows triggering the device between the both states in a non-volatile manner [5]. The experimental equipment used consisted of a Keithley 4200-SCS semiconductor parameter analyzer and a Lake Shore cryogenic probe station. Fig.1 shows current-voltage cycles measured at different temperatures; the averages values at each temperature, both in logarithmic and linear scale, are also shown. The functional window increases as temperature decreases. The evolutions of set and reset voltage values with temperature are depicted in Fig.2, whereas the current values (measured at 0.1 V) corresponding to the LRS and HRS can be seen in Fig.3. LRS resistance decreases as temperature increases, in agreement with semiconductor behaviour, probably due to a hopping conduction mechanism. Both set and reset voltages decrease as temperature increases; the reset process is smoother at high temperatures. The reduction in reset voltage variability as temperature increases is very notable. Finally, Fig. 4 shows a picture of the transient behaviour; in the right panel of the same figure, the amplitudes of the current transients in the reset state have been included in the external loop. To sum up, the resistive switching phenomena is studied in a wide temperature range. The LRS shows semiconducting behavior with temperature, most likely related to a hopping conduction mechanism. Switching voltages decrease as temperature increases, with a notable reduction in reset voltage variability. An excellent control of intermediate resistance state is shown through current transients at several voltages in the reset process. REFERENCES [1] M. Asif et al., Materials Today Electronics 1, 100004 (2022). [2] S. Slesazeck et al., Nanotechnology 30, 352003 (2019). [3] Z. Fang et al., IEEE Electron Device Letters 35, 9, 912-914 (2014). [4] H. Y. Lee et al., IEEE Electron Device Letters 31, 1, 44-46 (2010). [5] D. J. Wouters et al., Proceedings of the IEEE 103, 8, 1274-1288 (2015). Figure 1 KW - RRAM Y1 - 2024 U6 - https://doi.org/10.1149/MA2024-01211297mtgabs SN - 2151-2043 VL - MA2024-01 IS - 21 SP - 1297 EP - 1297 PB - The Electrochemical Society ER - TY - GEN A1 - Stella, Tommaso A1 - Webber, Heidi A1 - Rezaei, Ehsan Eyshi A1 - Asseng, Senthold A1 - Martre, Pierre A1 - Dueri, Sibylle A1 - Guarin, Jose Rafael A1 - Pequeno, Diego A1 - Calderini, Daniel A1 - Reynolds, Matthew A1 - Molero, Gemma A1 - Miralles, Daniel A1 - Garcia, Guillermo A1 - Slafer, Gustavo A. A1 - Giunta, Francesco A1 - Kim, Yean-Uk A1 - Wang, Chenzhi A1 - Ruane, Alex C. A1 - Ewert, Frank T1 - Wheat crop traits conferring high yield potential may also improve yield stability under climate change T2 - in silico Plants N2 - Increasing genetic wheat yield potential is considered by many as critical to increasing global wheat yields and production, baring major changes in consumption patterns. Climate change challenges breeding by making target environments less predictable, altering regional productivity and potentially increasing yield variability. Here we used a crop simulation model solution in the SIMPLACE framework to explore yield sensitivity to select trait characteristics (radiation use efficiency [RUE], fruiting efficiency and light extinction coefficient) across 34 locations representing the world’s wheat-producing environments, determining their relationship to increasing yields, yield variability and cultivar performance. The magnitude of the yield increase was trait-dependent and differed between irrigated and rainfed environments. RUE had the most prominent marginal effect on yield, which increased by about 45 % and 33 % in irrigated and rainfed sites, respectively, between the minimum and maximum value of the trait. Altered values of light extinction coefficient had the least effect on yield levels. Higher yields from improved traits were generally associated with increased inter-annual yield variability (measured by standard deviation), but the relative yield variability (as coefficient of variation) remained largely unchanged between base and improved genotypes. This was true under both current and future climate scenarios. In this context, our study suggests higher wheat yields from these traits would not increase climate risk for farmers and the adoption of cultivars with these traits would not be associated with increased yield variability. KW - climate change KW - climate risk KW - genetic yield potential KW - wheat KW - yield variability Y1 - 2023 U6 - https://doi.org/10.1093/insilicoplants/diad013 SN - 2517-5025 VL - 5 IS - 2 PB - Oxford University Press (OUP) ER - TY - GEN A1 - De Tomás Marín, Sergio A1 - Rodríguez-Calcerrada, Jesús A1 - Arenas-Castro, Salvador A1 - Prieto, Iván A1 - González, Guillermo A1 - Gil, Luis A1 - Garcia de la Riva, Enrique T1 - Fagus sylvatica and Quercus pyrenaica: Two neighbors with few things in common T2 - Forest Ecosystems KW - Environmental niche KW - European beech KW - Forest dynamics KW - Functional niche KW - Hypervolume KW - Pyrenean oak KW - Species coexistence KW - Sub-Mediterranean community Y1 - 2023 U6 - https://doi.org/10.1016/j.fecs.2023.100097 SN - 2197-5620 VL - 10 ER -