Chia-Sheng Hsu, Sou-Chi Chang, Dmitri E. Nikonov, I. Young, A. Naeemi
{"title":"Hysteresis-Free Negative Capacitance Effect in Metal-Ferroelectric-Insulator-Metal Capacitors with Dielectric Leakage and Interfacial Trapped Charges","authors":"Chia-Sheng Hsu, Sou-Chi Chang, Dmitri E. Nikonov, I. Young, A. Naeemi","doi":"10.1103/PHYSREVAPPLIED.15.034048","DOIUrl":"https://doi.org/10.1103/PHYSREVAPPLIED.15.034048","url":null,"abstract":"The negative capacitance (NC) stabilization of a ferroelectric (FE) material can potentially provide an alternative way to further reduce the power consumption in ultra-scaled devices and thus has been of great interest in technology and science in the past decade. In this article, we present a physical picture for a better understanding of the hysteresis-free charge boost effect observed experimentally in metal-ferroelectric-insulator-metal (MFIM) capacitors. By introducing the dielectric (DE) leakage and interfacial trapped charges, our simulations of the hysteresis loops are in a strong agreement with the experimental measurements, suggesting the existence of an interfacial oxide layer at the FE-metal interface in metal-ferroelectric-metal (MFM) capacitors. Based on the pulse switching measurements, we find that the charge enhancement and hysteresis are dominated by the FE domain viscosity and DE leakage, respectively. Our simulation results show that the underlying mechanisms for the observed hysteresis-free charge enhancement in MFIM may be physically different from the alleged NC stabilization and capacitance matching. Moreover, the link between Merz's law and the phenomenological kinetic coefficient is discussed, and the possible cause of the residual charges observed after pulse switching is explained by the trapped charge dynamics at the FE-DE interface. The physical interpretation presented in this work can provide important insights into the NC effect in MFIM capacitors and future studies of low-power logic devices.","PeriodicalId":8423,"journal":{"name":"arXiv: Applied Physics","volume":"20 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-12-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83640266","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Rattanachata, L. Nicolaï, H. Martins, G. Conti, M. Verstraete, M. Gehlmann, S. Ueda, Keisuke L. I. Kobayashi, I. Vishik, C. Schneider, C. Fadley, A. Gray, J. Minár, S. Nemšák
{"title":"Bulk electronic structure of lanthanum hexaboride (\u0000LaB6\u0000) by hard x-ray angle-resolved photoelectron spectroscopy","authors":"A. Rattanachata, L. Nicolaï, H. Martins, G. Conti, M. Verstraete, M. Gehlmann, S. Ueda, Keisuke L. I. Kobayashi, I. Vishik, C. Schneider, C. Fadley, A. Gray, J. Minár, S. Nemšák","doi":"10.1103/PhysRevMaterials.5.055002","DOIUrl":"https://doi.org/10.1103/PhysRevMaterials.5.055002","url":null,"abstract":"We investigate the bulk electronic structure of lanthanum hexaboride using tender-hard x-ray photoemission spectroscopy, measuring both core-level and angle-resolved valence-band spectra. We compare the La 3d core level spectrum to cluster model calculations in order to understand the bulk-like core-hole screening effects. The results show that the La 3d well-screened peak is at a lower binding energy compared to the main poorly-screened peak and the relative intensity between these peaks depends on how strong the hybridization is between La and B atoms. We show that the recoil effect, negligible in the soft x-ray regime, becomes prominent at higher kinetic energies for lighter elements, such as boron, but is still negligible for heavy nuclei, such as lanthanum. In addition, we report the bulk-like band structure of lanthanum hexaboride determined by tender-hard x-ray angle-resolved photoemission spectroscopy (HARPES). We compare HARPES experimental results to the free-electron final-state calculations and to the more precise one-step photoemission theory including matrix element and phonon excitation effects. The agreement between the features present in the experimental ARPES data and the theoretical calculations is remarkable. In addition, we consider the nature and the magnitude of phonon excitations in order to interpret HARPES experimental data measured at different temperatures and excitation energies. We demonstrate that one step theory of photoemission and HARPES experiments provide, at present, the only approach capable of probing, both experimentally and theoretically, true bulk-like electronic band structure of rare-earth hexaborides and strongly correlated materials.","PeriodicalId":8423,"journal":{"name":"arXiv: Applied Physics","volume":"67 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-12-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91367302","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}