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Journal ArticleDOI

The work function of the elements and its periodicity

01 Nov 1977-Journal of Applied Physics (American Institute of Physics)-Vol. 48, Iss: 11, pp 4729-4733
TL;DR: In the data for the 63 elements, trends that occur simultaneously in both the columns and the rows of the periodic table are shown to be useful in predicting correct values and also for identifying questionable data.
Abstract: A new compilation, based on a literature search for the period 1969–1976, is made of experimental data on the work function. For these 44 elements, preferred values are selected on the basis of valid experimental conditions. Older values, which are widely accepted, are given for 19 other elements on which there is no recent literature, and are so identified. In the data for the 63 elements, trends that occur simultaneously in both the columns and the rows of the periodic table are shown to be useful in predicting correct values and also for identifying questionable data. Several illustrative examples are given, including verifications of predictions published in 1950.
Citations
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Journal ArticleDOI
TL;DR: In this paper, a review of the literature in the area of alternate gate dielectrics is given, based on reported results and fundamental considerations, the pseudobinary materials systems offer large flexibility and show the most promise toward success.
Abstract: Many materials systems are currently under consideration as potential replacements for SiO2 as the gate dielectric material for sub-0.1 μm complementary metal–oxide–semiconductor (CMOS) technology. A systematic consideration of the required properties of gate dielectrics indicates that the key guidelines for selecting an alternative gate dielectric are (a) permittivity, band gap, and band alignment to silicon, (b) thermodynamic stability, (c) film morphology, (d) interface quality, (e) compatibility with the current or expected materials to be used in processing for CMOS devices, (f) process compatibility, and (g) reliability. Many dielectrics appear favorable in some of these areas, but very few materials are promising with respect to all of these guidelines. A review of current work and literature in the area of alternate gate dielectrics is given. Based on reported results and fundamental considerations, the pseudobinary materials systems offer large flexibility and show the most promise toward success...

5,711 citations

Journal ArticleDOI
TL;DR: In this paper, the Schottky barrier heights and band offsets for high dielectric constant oxides on Pt and Si were calculated and good agreement with experiment is found for barrier heights.
Abstract: Wide-band-gap oxides such as SrTiO3 are shown to be critical tests of theories of Schottky barrier heights based on metal-induced gap states and charge neutrality levels. This theory is reviewed and used to calculate the Schottky barrier heights and band offsets for many important high dielectric constant oxides on Pt and Si. Good agreement with experiment is found for barrier heights. The band offsets for electrons on Si are found to be small for many key oxides such as SrTiO3 and Ta2O5 which limit their utility as gate oxides in future silicon field effect transistors. The calculations are extended to screen other proposed oxides such as BaZrO3. ZrO2, HfO2, La2O3, Y2O3, HfSiO4, and ZrSiO4. Predictions are also given for barrier heights of the ferroelectric oxides Pb1−xZrxTiO3 and SrBi2Ta2O9 which are used in nonvolatile memories.

1,947 citations

Journal ArticleDOI
TL;DR: In this paper, the fabrication, properties, and solar energy applications of highly ordered TiO 2 nanotube arrays made by anodic oxidation of titanium in fluoride-based electrolytes are reviewed.

1,905 citations

Journal ArticleDOI
TL;DR: This paper demonstrates an inverter, a NAND gate, a static random access memory, and a five-stage ring oscillator based on a direct-coupled transistor logic technology based on the semiconducting nature of molybdenum disulfide.
Abstract: Two-dimensional (2D) materials, such as molybdenum disulfide (MoS2), have been shown to exhibit excellent electrical and optical properties. The semiconducting nature of MoS2 allows it to overcome the shortcomings of zero-bandgap graphene, while still sharing many of graphene’s advantages for electronic and optoelectronic applications. Discrete electronic and optoelectronic components, such as field-effect transistors, sensors, and photodetectors made from few-layer MoS2 show promising performance as potential substitute of Si in conventional electronics and of organic and amorphous Si semiconductors in ubiquitous systems and display applications. An important next step is the fabrication of fully integrated multistage circuits and logic building blocks on MoS2 to demonstrate its capability for complex digital logic and high-frequency ac applications. This paper demonstrates an inverter, a NAND gate, a static random access memory, and a five-stage ring oscillator based on a direct-coupled transistor logic...

1,555 citations

Journal ArticleDOI
TL;DR: In this article, a review of the development of high-k gate oxides such as hafnium oxide (HFO) and high-K oxides is presented, with the focus on the work function control in metal gate electrodes.
Abstract: The scaling of complementary metal oxide semiconductor transistors has led to the silicon dioxide layer, used as a gate dielectric, being so thin (14?nm) that its leakage current is too large It is necessary to replace the SiO2 with a physically thicker layer of oxides of higher dielectric constant (?) or 'high K' gate oxides such as hafnium oxide and hafnium silicate These oxides had not been extensively studied like SiO2, and they were found to have inferior properties compared with SiO2, such as a tendency to crystallize and a high density of electronic defects Intensive research was needed to develop these oxides as high quality electronic materials This review covers both scientific and technological issues?the choice of oxides, their deposition, their structural and metallurgical behaviour, atomic diffusion, interface structure and reactions, their electronic structure, bonding, band offsets, electronic defects, charge trapping and conduction mechanisms, mobility degradation and flat band voltage shifts The oxygen vacancy is the dominant electron trap It is turning out that the oxides must be implemented in conjunction with metal gate electrodes, the development of which is further behind Issues about work function control in metal gate electrodes are discussed

1,520 citations

References
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Journal ArticleDOI
D. E. Eastman1
TL;DR: In this article, photoelectric work functions of polycrystalline films of Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Y, Zr, Nb, Mo, Pd, Ag, La, Ce, Nd, Sm, Eu, Gd, Hf, Pt, and Au are reported.
Abstract: Photoelectric work functions of polycrystalline films of Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Y, Zr, Nb, Mo, Pd, Ag, La, Ce, Nd, Sm, Eu, Gd, Hf, Pt, and Au are reported.

588 citations

Journal ArticleDOI
TL;DR: In this article, the work functions of the bulk crystals and of silver films formed upon them by auto-epitaxy were determined photoelectrically, and the results support the Smoluchowski correlation of work function with surface atom density.
Abstract: (100) and (110) single crystals of silver were cleaned by electron and argon-ion bombardment in ultra-high vacuum. The work functions of the bulk crystals, and of silver films formed upon them by autoepitaxy, were determined photoelectrically. The bulk crystals had work functions of (4.64 ± 0.02) eV and (4.52 ± 0.02) eV respectively. The effect of the deposition of silver films was to reduce the work function, but continued cycles of deposition and annealing at 500 to 600 K caused the work function to return to a value very close to that of the bulk crystal. An annealed film of silver deposited in stages on a mica substrate at 425 K had a work function of (4.72 ± 0.02) eV, corresponding to that of the (111) silver surface. If the mica remained at room temperature during deposition, the work function was about 4.5 eV. The work function of a thick polycrystalline film of silver on quartz was (4.26 ± 0.02) eV. The results support the Smoluchowski correlation of work function with surface atom density.

223 citations

Journal ArticleDOI
TL;DR: The work function φ is a periodic function of atomic number, as shown clearly by a new compilation of published data for 57 elements as mentioned in this paper, and the progressive rise and fall of work function values throughout the table of the elements appears to be sufficiently regular to permit approximations to be made of values for the metallic and semimetallic elements on which no data has yet been published.
Abstract: Like the chemical properties of the elements, the work function φ is a periodic function of atomic number, as shown clearly by a new compilation of published data for 57 elements. The progressive rise and fall of work function values throughout the table of the elements appears to be sufficiently regular to permit approximations to be made of values for the metallic and semimetallic elements on which no data has yet been published. Since the first ionization potential Ei and electrode potential E0 exhibit a similar periodic function of atomic number, a striking resemblance exists among the respective plots of φ, Ei, and E0.

183 citations

Journal ArticleDOI
TL;DR: In this paper, the anisotropic work function of smooth (100), smooth (111), and (110) faces of a single crystal were cleaned through a mild cyclic treatment of ion bombardment and annealing.

176 citations