Ten years after the first report on ferroelectricity in HfO_(2),researchers are still occupied unraveling the different causes behind this phenomenon.Among them,oxygen related defects seem to play a major role,affecti...Ten years after the first report on ferroelectricity in HfO_(2),researchers are still occupied unraveling the different causes behind this phenomenon.Among them,oxygen related defects seem to play a major role,affecting both crystalline phase formation and performance of HfO_(2)-based devices.This review surveys the available literature and provides a broad picture on the topic,starting with an overview of existing oxygen-related defects,assessing the extensive calculations and experimental reports on phase stabilization in both undoped and doped HfO_(2) and concluding with a discussion of device reliability involving oxygen vacancies,first in more classical HfO_(2) applications such as MOSFET high-k metal gate and resistive switching devices and later in the three major groups of ferroelectric non-volatile memory devices.展开更多
Insight into the origin of process-related properties like small-scale inhomogeneities is key for material optimization.Here,we analyze DFT calculations of randomly doped HfO_(2) structures with Si,La,and VO and relat...Insight into the origin of process-related properties like small-scale inhomogeneities is key for material optimization.Here,we analyze DFT calculations of randomly doped HfO_(2) structures with Si,La,and VO and relate them to the kind of production process.Total energies of the relevant ferroelectric Pbc2_(1) phase are compared with the competing crystallographic phases under the influence of the arising local inhomogeneities in a coarse-grained approach.The interaction among dopants adds to the statistical effect from the random positioning of the dopants.In anneals after atomic layer or chemical solution deposition processes,which are short compared to ceramic process tempering,the large energy variations remain because the dopants do not diffuse.Since the energy difference is the criterion for the phase stability,the large variation suggests the possibility of nanoregions and diffuse phase transitions because these local doping effects may move the system over the paraelectric-ferroelectric phase boundary.展开更多
基金Sony Semiconductor Solutions Corporation funding support towards this researchfunded by the German Research Foundation(DFG)–project number 433647091/Zeppelin+2 种基金partially financed by the Saxon State government out of the State budget approved by the Saxon State Parliamentsupported by the National Research Foundation of Korea funded by the Ministry of Science and ICT(Grant number:2020R1C1C1008193,2020M3F3A2A01081593)the Gauss Centre for Supercomputing e.V.(http://www.gauss-centre.eu)for funding by providing computing time on the GCS Supercomputer SuperMUC-NG at Leibniz Supercomputing Centre(http://www.lrz.de)under the grant:pr27su.
文摘Ten years after the first report on ferroelectricity in HfO_(2),researchers are still occupied unraveling the different causes behind this phenomenon.Among them,oxygen related defects seem to play a major role,affecting both crystalline phase formation and performance of HfO_(2)-based devices.This review surveys the available literature and provides a broad picture on the topic,starting with an overview of existing oxygen-related defects,assessing the extensive calculations and experimental reports on phase stabilization in both undoped and doped HfO_(2) and concluding with a discussion of device reliability involving oxygen vacancies,first in more classical HfO_(2) applications such as MOSFET high-k metal gate and resistive switching devices and later in the three major groups of ferroelectric non-volatile memory devices.
基金The Deutsche Forschungsgemeinschaft(German Research Foundation)has funded this research in the frame of the project Inferox II(Project MI 1247/11-2)This work was supported by the Deutsche Forschungsgemeinschaft(German Research Foundation(DFG)-Project 393121356)and the Munich University of Applied Sciences(MUAS)through the Open Access Publishing program.
文摘Insight into the origin of process-related properties like small-scale inhomogeneities is key for material optimization.Here,we analyze DFT calculations of randomly doped HfO_(2) structures with Si,La,and VO and relate them to the kind of production process.Total energies of the relevant ferroelectric Pbc2_(1) phase are compared with the competing crystallographic phases under the influence of the arising local inhomogeneities in a coarse-grained approach.The interaction among dopants adds to the statistical effect from the random positioning of the dopants.In anneals after atomic layer or chemical solution deposition processes,which are short compared to ceramic process tempering,the large energy variations remain because the dopants do not diffuse.Since the energy difference is the criterion for the phase stability,the large variation suggests the possibility of nanoregions and diffuse phase transitions because these local doping effects may move the system over the paraelectric-ferroelectric phase boundary.
