TY - CHAP A1 - Schmeißer, Dieter A1 - Kot, Małgorzata A1 - Corrêa, Silma Alberton A1 - Das, Chittaranjan A1 - Henkel, Karsten ED - Wandelt, Klaus T1 - Interface Potentials, Intrinsic Defects, and Passivation Mechanisms in Al₂O₃, HfO₂, and TiO₂ Ultrathin Films T2 - Encyclopedia of Interfacial Chemistry: Surface Science and Electrochemistry, vol. 3.1 N2 - We study the electronic structure of ultrathin Al₂O₃, HfO₂, and TiO₂ ALD films by resonant photoelectron spectroscopy. We identify intrinsic defects which are responsible for the active sites in interface reactions, for the incorporation of intrinsic charges, and for the formation of local dipole momenta. All of these features determine the surface potentials and the reactivity of the surface of the atomic layer deposition coated systems. We give examples of charges and dipoles in Al₂O₃, on a study of the surface potentials in HfO₂, and relate the intrinsic defects in TiO₂ to their electrochemical relevance. KW - Atomic layer deposition (ALD) KW - Resonant photoelectron spectroscopy (resPES) KW - Band scheme KW - Interface potential KW - Intrinsic charges KW - Intrinsic defects KW - Partial density of states (pDOS) KW - Exciton KW - Polaron KW - Ligand-to-metal charge transfer KW - Aluminium oxide (Al₂O₃) KW - Hafnium oxide (HfO₂) KW - Titanium Oxide (TiO₂) Y1 - 2018 SN - 978-0-12-809739-7 SN - 978-0-12-814984-3 U6 - https://doi.org/10.1016/B978-0-12-409547-2.14119-8 SP - 162 EP - 171 PB - Elsevier CY - Oxford ER - TY - GEN A1 - Alberton Corrêa, Silma A1 - Brizzi, Simone A1 - Schmeißer, Dieter T1 - Spectroscopic investigation of the electronic structure of thin atomic layer deposition HfO2 films T2 - Journal of Vacuum Science & Technology A N2 - The electronic structure of HfO2 thin films is investigated employing resonant photoelectron spectroscopy (resPES). The detailed analysis of the O1s resonance profile enables the determination of the partial density of states for the valence and the conduction bands as well as the electronic band gap to be 6.2 eV. The position of the charge neutrality level is evaluated. Thereby, it is demonstrated that the resPES data are able to combine information both for the valence as well as for the conduction band states. In addition, evidences for intrinsic in-gap states attributed to polaronic and charge transfer states are given. Electronic charges within the atomic layer deposition-HfO2films are identified, pointing out that the amount of charges is essential to determine the accurate position of the surface potentials. KW - resonant photoelectron spectroscopy KW - hafnium oxide KW - atomic layer deposition KW - partial density of states KW - electronic band gap Y1 - 2016 U6 - https://doi.org/10.1116/1.4935338 SN - 0734-2101 SN - 1520-8559 VL - 34 IS - 1 SP - 01A117-1 EP - 01A117-8 ER - TY - GEN A1 - Pitthan, E. A1 - dos Reis, R. A1 - Alberton Corrêa, Silma A1 - Schmeißer, Dieter A1 - Boudinov, H. I. A1 - Stedile, F. C. T1 - Influence of CO annealing in metal-oxide-semiconductor capacitors with SiO2 films thermally grown on Si and on SiC T2 - Journal of Applied Physics N2 - Understanding the influence of SiC reaction with CO, a by-product of SiC thermal oxidation, is a key point to elucidate the origin of electrical defects in SiC metal-oxide-semiconductor (MOS) devices. In this work, the effects on electrical, structural, and chemical properties of SiO2/Si and SiO2/SiC structures submitted to CO annealing were investigated. It was observed that long annealing times resulted in the incorporation of carbon from CO in the Si substrate, followed by deterioration of the SiO2/Si interface, and its crystallization as SiC. Besides, this incorporated carbon remained in the Si surface (previous SiO2/Si region) after removal of the silicon dioxide film by HF etching. In the SiC case, an even more defective surface region was observed due to the CO interaction. All MOS capacitors formed using both semiconductor materials presented higher leakage current and generation of positive effective charge after CO annealings. Such results suggest that the negative fixed charge, typically observed in SiO2/SiC structures, is not originated from the interaction of the CO by-product, formed during SiC oxidation, with the SiO2/SiC interfacial region. KW - metal-oxide-semiconductor KW - silicon KW - silicon carbide KW - CO annealing Y1 - 2016 U6 - https://doi.org/10.1063/1.4939836 SN - 0021-8979 SN - 1089-7550 IS - 119 SP - 025307-1 EP - 025307-6 ER - TY - GEN A1 - Corrêa, Silma Alberton A1 - Brizzi, Simone A1 - Schmeißer, Dieter T1 - Depicting the Electronic Structure of HfO₂ Films by Spectroscopic Techniques T2 - ECS Transactions N2 - The electronic structure of HfO₂ films was investigated. The partial density of states for the valence and the conduction bands was determined by the detailed analysis of the O1s resonance profile by resonant photoelectron spectroscopy. The positions of valence band maximum and conduction band minimum, the excitation range for the polaronic states and the range of charge transfer band were found to be not influenced by the preparation conditions. The band gap was determined to be 6.2 eV and the energy of the charge neutrality level (referred to vacuum level) was determined as 4.7 eV. The Fermi level position was observed to vary about 1.2 eV depending on the preparation conditions, which indicates the presence of charges within the films. KW - HfO₂ KW - resonant photoelectron spectroscopy (resPES) KW - electronic structure KW - partial density of states KW - charge neutrality level Y1 - 2016 U6 - https://doi.org/10.1149/07506.0145ecst SN - 1938-6737 SN - 1938-5862 VL - 75 IS - 6 SP - 145 EP - 153 ER - TY - CHAP A1 - Alberton Corrêa, Silma A1 - Brizzi, Simone A1 - Tallarida, Massimo A1 - Schmeißer, Dieter T1 - Spectroscopic investigation of the electronic structure of HfO2 thin films T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - HfO2 is of current interest as a material for memristive and ferroelectric devices. In this work, we used spectroscopic techniques to evaluate the electronic structure and defects mechanisms in thin HfO2 films deposited by atomic layer deposition and by metal-organic chemical vapour deposition. The partial density of states for the valence and the conduction bands was determined by the detailed analysis of the O1s resonance profile by resonant photoelectron spectroscopy. From the relative contributions we find a CNL 6.5 eV referred to Evac. We also find that the positions of valence band maximum and conduction band minimum, the excitation range for the polaronic states and the range of charge transfer band were not influenced by the preparation conditions. All films exhibit a band gap of 6.2 eV. However, the Fermi level position was found to vary within about 1.2 eV depending on the preparation conditions, which we argue that is due to the presence of charges within the films. This explains why the position of the Fermi level depends on the individual preparation parameters. KW - electronic structure KW - HfO2 Y1 - 2015 UR - http://www.dpg-verhandlungen.de/year/2015/conference/berlin/part/ds/session/36/contribution/106?lang=en SN - 0420-0195 SP - S. 211 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Rouissi, Zied A1 - Brizzi, Simone A1 - Alberton Corrêa, Silma A1 - Tallarida, Massimo A1 - Schmeißer, Dieter T1 - Comparison of charge neutrality level of Cu/CuO/HfO2 and Si/SiO2/HfO2 T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - Copper Oxide (CuO) is a promising metal oxide semiconductor, which can be used in different applications, such as catalysis, solar energy conversion, and water splitting. In this work, we use resonance photoemission spectroscopy (ResPES) to analyse the electronics properties of HfO2 films deposited on Cu/CuO and Si/SiO2. For that, we deposited 10 cycles of HfO2 by atomic layer deposition (ALD) on Cu/CuO and Si/SiO2 samples and investigated the density states for the valence and conduction bands which were determined by the detailed analysis of the O1s resonance profile obtained by ResPES. We compared the positions of valence band maximum and conduction band minimum, the excitation range for the polaronic states and the range of charge transfer band in Cu/CuO/HfO2 and Si/SiO2/HfO2. Also, we determined the band gap and the charge neutrality level (CNL). KW - charge neutrality level (CNL) KW - resonant photoelectron spectroscopy KW - HfO2 Y1 - 2015 UR - http://www.dpg-verhandlungen.de/year/2015/conference/berlin/part/ds/session/36/contribution/47?lang=en SN - 0420-0195 SP - 208 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER - TY - CHAP A1 - Alberton Corrêa, Silma A1 - Brizzi, Simone A1 - Tallarida, Massimo A1 - Schmeißer, Dieter T1 - Charging effect in HfO2 films deposited on SiO2/Si by atomic layer deposition T2 - Verhandlungen der Deutschen Physikalischen Gesellschaft N2 - Thin films of hafnium oxide (HfO2) deposited by atomic layer deposition (ALD) have been studied extensively as a high-k replacement for the SiO2 gate in field effect transistors. The use of ALD process allows one to grow homogeneous thin films at low temperatures with a precise control of thickness [1]. Some important electrical considerations for the application of a high-k dielectric include the presence of fixed charge (Qf) and charge trapping in the dielectric. For instance, in the case of Al2O3 thin films deposited on Si, the thickness of the interfacial SiO2 layer was identified as a key fundamental parameter determining Qf [2]. A similar trend can be also expected in HfO2/Si structures. Therefore, in this work, we proposed an in situ evaluation of photon induced charge trapping in HfO2 films deposited on SiO2/Si structures. For that, tetrakis-di-methyl-amino-hafnium (TDMAHf) and H2O were employed as precursors to deposit HfO2 films on SiO2/Si samples with variable thickness of the SiO2 interlayer. Measurements were performed by Synchrotron Radiation Photoemission Spectroscopy (SR-PES). Results indicated that the charging process is dependent on the thickness of the SiO2 interlayer and on the quality of the HfO2 film. [1] M. Leskelä and M. Ritala, Thin Solid Films 409, 138 (2002). [2] G. Dingemans et al., J. Appl. Phys. 110, 093715 (2011). KW - Charging KW - HfO2 KW - atomic layer deposition (ALD) Y1 - 2014 UR - http://www.dpg-verhandlungen.de/year/2014/conference/dresden/part/ds/session/49/contribution/10?lang=en SN - 0420-0195 PB - Deutsche Physikalische Gesellschaft CY - Bad Honnef ER -