Effect of O-vacancy defects on the Schottky barrier heights in Ni/SiO2 and Ni/HfO2 interfaces

Noh, Hyeon‐Kyun; Oh, Young-Jun; Chang, Kee-Joo

doi:10.1016/j.physb.2011.08.079

Cited by 3 publications

(3 citation statements)

References 21 publications

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“…26,27 The calculated decay lengths are similar to those (1.1-1.2Å) obtained for Ni/HfO 2 interfaces. 28,29 The minimum decay length occurs at the charge neutrality level (E CNL ), which corresponds to the branch point of complex band structure. 4 For both the Ti-O and N-Hf interfaces, we find the minimum decay lengths of about 1.01Å at 2.4 eV above the valence band edge of HfO 2 .…”

Section: B Intrinsic Metal-induced Gap Statesmentioning

confidence: 99%

Hybrid functional versus quasiparticle calculations for the Schottky barrier and effective work function at TiN/HfO2interface

Lee

Noh

et al. 2013

Phys. Rev. B

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We investigate the Schottky barrier and effective work function (EWF) at TiN/HfO 2 interface through density functional calculations. For different interfaces that consist of either Ti-O or N-Hf interface bonds, the intrinsic metal-induced gap states are nearly independent of the interface structure, with similar decay lengths into the oxide. Due to the weak Fermi-level pinning, the EWF is more sensitive to the extrinsic effect of interface bonding. As N-rich interface bonds are replaced by O-rich bonds, the EWF decreases by up to 0.36 eV, which is attributed to the formation of opposing interface dipoles. To improve the band gap and EWF, we perform both hybrid functional and quasiparticle (QP) calculations. In the GW 0 approximation, in which the Green's function is self-consistently calculated by updating only QP energies and the full frequency-dependent dielectric function is used, the agreement of the EWF with experiment is greatly improved, while QP calculations at the G 0 W 0 level or using the plasmon-pole dielectric function tend to overestimate the EWF. In the self-consistent GW approach, in which both QP energies and wave functions are updated in iterations, the band gap is overestimated, resulting in the lower EWF. On the other hand, the EWF is severely underestimated with the hybrid functional because of the larger shift of the valence band edge level of HfO 2 .

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Section: B Intrinsic Metal-induced Gap Statesmentioning

confidence: 99%

Hybrid functional versus quasiparticle calculations for the Schottky barrier and effective work function at TiN/HfO2interface

Lee

Noh

et al. 2013

Phys. Rev. B

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“…The so-called extended Frenkel pair defect is found to be quite unfavorable for some metals like TiN [30] and Pt [31], it has been found to be energetically favorable for several other metals such as molybdenum [32], rhodium and nickle [33], and hafnium metal [34]. The defects such as oxygen vacancy and interstitial atoms segregating near metal-HfO2 interfaces, cause variation of interface EWF via changing the interface dipole strength [22,[35][36][37]. Furthermore, the EWF of pMOS gate is sensitive to oxygen vacancy inside the metal/high-k interface [19,22].…”

mentioning

confidence: 99%

“…Recently, the metal-HfO2 interfaces with oxygen vacancy have been investigated using first-principles calculations [18,31,32,36,37]. Cho et al have found that oxygen vacancies are strongly attracted to the interface, in particular for the metal with high EWF, and the interfacial segregation of vacancies significantly affects the EWF of metals [31,36].…”

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Effects of intrinsic defects on effective work function for Ni/HfO2 interfaces

Zhong

Zhang

et al. 2016

Materials Chemistry and Physics

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The effective work functions and formation energies for Ni/HfO2 interfaces with and without defects, including interfacial intrinsic atom substitution and atom vacancy in interfacial layer were studied by first-principles methods based on density functional theory (DFT). The calculated results of the formation energies indicate that the interfaces with O-Ni combining bonds in the interfacial region are more energetically favorable and a small amount O vacancy is comparatively easy to form in O-Ni interface, especially under O-rich situation. Moreover, the results of our calculations also reveal that, (1) the effective work functions strongly depend on the type of interface, interface roughness and atom substitution content in the interface region;(2) for Hf-Ni interfaces, two calculated effective work functions without and with Ni substitutions in whole interfacial Hf layer are good for nMOS and pMOS effective work function (EWF) engineering, respectively; (3) the EWFs are sensitive to Hf vacancy rather than Ni vacancy in interfacial layer for Hf-Ni interfaces; (4) oxygen vacancies can result in a © 2016. This manuscript version is made available under the Elsevier user license http://www.elsevier.com/open-access/userlicense/1.0/ 2 decrease of effective work function for O-Ni interfaces. Additionally, we establish an expectedtheoretical relationship that variations of the EWFs are in proportion to that of interface dipole density. Finally, ionic valence state and occupied state are used to qualitatively analyze and explain the effects of interfacial defects on the EWF in metal-oxide interfaces. Our work suggests that controlling interfacial intrinsic atom substitution and interface roughness are attractive and promising ways for modulating the effective work function of Ni/HfO2 interfaces. IntroductionTo solve the problems arising from the aggressive size downscaling of metal-oxide-semiconductor field-effect transistor (MOSFET), both high dielectric constant "high-k" gate dielectric and metal gate electrode are required to replace the traditional SiO2 gate dielectric and polycrystalline Si, respectively [1,2]. Because of its high dielectric constant, excellent thermal stability and compatibility with various technical requirements, Hafnium oxide (HfO2) has emerged as one of the most preferred gate oxides in high-k metal gate technology [2-4]. While for desirable metal gate, an appropriate effective work function needs to satisfy the requirement that it lies near the valence and conduction band edges of Si substrate (about 4.1eV and 5.2eV for negative MOS [nMOS] and positive MOS [pMOS], respectively) [5]. There have been many studies [6-16] on tuning the effective work function (EWF) of metal-high-k gate stacks and several accompanying possible modulation methods for the EWF, such as binary 3 alloys [6], bilayer metal gate technology [7], and atomic dopant [8][9][10][11][12][13][14][15]. However, even so, the EWF is difficult to control, especially for pMOS, due to its extreme sensitivity to a number of factors th...

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Annealing modulated microstructural and electrical properties of plasma-enhanced atomic layer deposition-derived HfO2/SiO2 nanolaminates on AlGaN/GaN

Wang,

Li,

Chen

et al. 2023

Journal of Vacuum Science &Amp; Technology A

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In current work, HfO2/SiO2 nanolaminates and HfO2 films were grown on AlGaN/GaN substrates via plasma-enhanced atomic layer deposition. A comparative study of how rapid thermal annealing modulates the microstructural and electrical properties of both films has been presented. It is found that the HfO2/SiO2 nanolaminate keeps an amorphous structure when thermally treated below 600 °C, whereas crystal grains appear within the 800 °C annealed sample. High-temperature annealing facilitates the transformation from Hf–O and Si–O to Hf–O–Si in the HfO2/SiO2 nanolaminates, forming an HfSiO4 composite structure simultaneously. The 800 °C annealed HfO2/SiO2 shows a low k value and large leakage current density. While the 600 °C annealed HfO2/SiO2 possesses an effective dielectric constant of 18.3, a turn-on potential of 9.0 V, as well as a leakage density of 10−2 μA/cm2 at gate biases of both −10 and 2 V, revealing good potential in fabricating high electron mobility transistors.

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Effect of O-vacancy defects on the Schottky barrier heights in Ni/SiO2 and Ni/HfO2 interfaces

Cited by 3 publications

References 21 publications

Hybrid functional versus quasiparticle calculations for the Schottky barrier and effective work function at TiN/HfO2interface

Hybrid functional versus quasiparticle calculations for the Schottky barrier and effective work function at TiN/HfO2interface

Effects of intrinsic defects on effective work function for Ni/HfO2 interfaces

Annealing modulated microstructural and electrical properties of plasma-enhanced atomic layer deposition-derived HfO2/SiO2 nanolaminates on AlGaN/GaN

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