Hole conduction and valence‐band structure of Si3N4 films on Si
TL;DR: In this article, X-ray photo-emission spectroscopy (XPS) was performed on thin films of Si3N4 deposited on Si using carrier injection from low-energy corona ions and a shallow junction detector.
Abstract: Transport measurements were performed on thin films of Si3N4 deposited on Si using carrier injection from low‐energy corona ions and a shallow junction detector. Large hole conduction is found for both corona polarities. Examination of the electronic structure of Si3N4 by x‐ray photoemission spectroscopy (XPS or ESCA) reveals one broad structure 10 eV wide (FWHM) at the top of the valence bands which results from the bonding of the Si 3s, Si 3p, and N 2p orbitals. This finding is consistent with the hole conduction we observe. The XPS results are compared with those from amorphous SiO2. The tops of the valence band of Si3N4 and SiO2 are found to lie 1.5±0.2 eV and 4.5±0.2 eV, respectively, below the Fermi level of a thin overlayer of gold.
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TL;DR: The bulk modulus of \ensuremath{\beta}-${\mathrm{C}}_{3}$ is found to be comparable to diamond, and its moderately large cohesive energy suggests that the prototype structure may be metastable.
Abstract: We present a first-principles pseudopotential study of the structural and electronic properties of \ensuremath{\beta}-${\mathrm{Si}}_{3}$${\mathrm{N}}_{4}$ and the hypothetical compound \ensuremath{\beta}-${\mathrm{C}}_{3}$${\mathrm{N}}_{4}$. \ensuremath{\beta}-${\mathrm{C}}_{3}$${\mathrm{N}}_{4}$, which is ${\mathrm{C}}_{3}$${\mathrm{N}}_{4}$ in the \ensuremath{\beta}-${\mathrm{Si}}_{3}$${\mathrm{N}}_{4}$ structure, with C substituted for Si, is used as a prototype for investigating the properties of possible covalent C-N solids. The calculated lattice constant, bulk modulus, and electronic band structure of \ensuremath{\beta}-${\mathrm{Si}}_{3}$${\mathrm{N}}_{4}$ are in good agreement with experimental results. This gives support for the predicted properties of \ensuremath{\beta}-${\mathrm{C}}_{3}$${\mathrm{N}}_{4}$. The bulk modulus of \ensuremath{\beta}-${\mathrm{C}}_{3}$${\mathrm{N}}_{4}$ is found to be comparable to diamond, and its moderately large cohesive energy suggests that the prototype structure may be metastable. Although the crystal structure and the valencies of the constituent atoms are similar in \ensuremath{\beta}-${\mathrm{Si}}_{3}$${\mathrm{N}}_{4}$ and \ensuremath{\beta}-${\mathrm{C}}_{3}$${\mathrm{N}}_{4}$, the electronic bonding properties in these two solids are found to differ. The large core size and repulsive p pseudopotential of the second-row element, Si, results in a more ionic Si-N bond compared with a covalent C-N bond.
903 citations
TL;DR: In this paper, the valence band density of electron states shows a lone pair band and a deeper bonding band as usual, impurities have a greater effect in the nitride than in conventional lone pair semiconductors.
Abstract: Silicon Nitride is found to have a valence band maximum of nitrogen lone pair p electrons because of the planar nitrogen site. This contrasts with the usual lone pair semiconductors, such as SiO2, caused by a p4 valence configuration. Consequently although the valence band density of electron states shows a lone pair band and a deeper bonding band as usual, impurities have a greater effect in the nitride than in conventional lone pair semiconductors. Hole transport is also discussed.
246 citations
IBM1
TL;DR: In this article, a model for electron tunneling based on electrons being confined within the lowest subband at the SiSiO 2 interface is discussed and compared to the Fowler-Nordheim expression.
Abstract: Accurate measurements of electron tunneling at the SiSiO 2 interface were performed using the decay of surface potential following charging of the exposed oxide surface by positive corona ions. The surface potential was measured by an automated Kelvin-probe arrangement. Comparison of results for various substrate dopings, crystallographic orientations and oxide film thicknesses is presented. A model for tunneling based on electrons being confined within the lowest subband at the SiSiO 2 interface is also discussed and compared to the Fowler-Nordheim expression.
245 citations
161 citations
TL;DR: In this article, the voltage and time-dependence of tunneling currents in polysilicon-oxide-nitride-oxide semiconductor structures have been investigated using a shallow junction technique.
Abstract: The voltage- and time-dependence of the tunneling currents in polysilicon–oxide–nitride–oxide semiconductor structures have been investigated. Electron and hole contributions were separated using a shallow junction technique. The standard tunneling model for charge injection was successfully applied to describe the observed threshold voltage shifts. For both positive and negative gate voltages, the time-dependence of the current density through the tunneling oxide is given by a simple analytical equation. This equation is characterized by an initial time constant and an asymptotic t−1-dependence. At large programming times the current density follows the t−1-dependence, independent of the tunneling oxide thickness and applied voltage. Under positive polarity (write) electrons are injected from the substrate. Under negative polarity (erase) and previous injection electron back-tunneling rather than hole injection is dominant at the beginning of erasing. At the end of erasing, steady-state conduction can be...
129 citations
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TL;DR: In this paper, it was shown that at any given temperature and electric field, the current transport is essentially independent of the substrate material, the film thickness, or the polarity of the electrodes.
Abstract: Measurements of current‐voltage characteristics have been performed on Au‐Si3N4‐Mo and Au‐Si3N4‐Si (degenerate substrate) structures of various nitride‐film thicknesses from 300 A to 3000 A and over a range of temperatures. The films are deposited by the process of reaction of SiCl4 with NH3. It is found that at any given temperature and electric field, the current transport is essentially independent of the substrate material, the film thickness, or the polarity of the electrodes.It is proposed that the current‐transport mechanisms are bulk controlled rather than electrode controlled. The conduction‐current density, J, is the sum of three contributions: J = J1+J2+J3, where J1∼E exp {−q[φ1 − (qE/πe0ed)½]/ kT}, J2∼E2 exp (−E2/E), and J3∼E exp (−qφ3/kT). At high fields and high temperatures J1 dominates the current conduction (the Poole‐Frenkel effect or internal Schottky effect); one obtains a barrier height of (1.3±0.2) V for φ1 and a value of 5.5±1 for the dynamic dielectric constant ed. At high fields a...
445 citations
IBM1
TL;DR: The complete valence band in amorphous Si${\mathrm{O}}_{2}$ has been examined by photoelectron spectroscopy at photon energies of 21.2, 26.9, 40.8, and 1486.6 eV as mentioned in this paper.
Abstract: The complete valence band in amorphous Si${\mathrm{O}}_{2}$ has been examined by photoelectron spectroscopy at photon energies of 21.2, 26.9, 40.8, and 1486.6 eV. The spectra show emission from an 11.2-eV-wide $p$-derived valence band and from the oxygen $2s$ level at 20.2 eV below the valence-band edge. Four pieces of structure in the $p$ bands are related to the single bonding and the two nonbonding orbitals of the ${\mathrm{O}}^{\ensuremath{-}\ensuremath{-}}$ ion. A narrow, nonbonding level found at the valence-band edge may cause lattice trapping of valence-band holes.
189 citations
TL;DR: In this paper, results of charge−centroid measurements on thin-oxide MNOS devices are interpreted with a charge trapping model, leading to values for the nitride trap density, capture cross section, and average trapping distance of 6×1018/cm3, 5×10−13 cm2, and 35 A, respectively.
Abstract: Previous charge−centroid studies of MNOS devices have shown that electrons injected into the insulator structure from the silicon are trapped not solely at the dielectric interface, but can be distributed over nearly the entire nitride thickness. In this paper, results of charge−centroid measurements on thin−oxide MNOS devices are interpreted with a charge trapping model, leading to values for the nitride trap density, capture cross section, and average trapping distance of 6×1018/cm3, 5×10−13 cm2, and 35 A, respectively.
141 citations
TL;DR: In this article, the first measurement of hole mobility and its temperature dependence in thermally grown SiO2 on Si was reported and found to follow μ≃20 exp(−0.6eV/kT) cm2/V sec.
Abstract: The first measurement of the hole mobility and its temperature dependence in thermally grown SiO2 on Si is reported and found to follow μ≃20 exp(−0.6eV/kT) cm2/V sec. In agreement with previous studies, the energy required to form an electron−hole pair with ionizing radiation is found to be field dependent and at very high fields is in the range of 18 eV/electron−hole pair, and is nearly temperature independent from 77 to 370 °K.
136 citations
TL;DR: In this paper, an analytical theory for the switching time constant of thin oxide MNOS structures is derived and curves of the switching-time constant versus the nitride field are computed, which are useful in the design of MNOS-memory transistors.
Abstract: The properties of thin oxide MNOS structures are studied. An analytical theory for the switching time constant is derived and curves of the switching time constant versus the nitride field are computed. These curves are useful in the design of MNOS-memory transistors. The theory is compared with experiments. The normal current in the thin oxide MNOS structures is assumed to be a modified Fowler-Nordheim current. At small oxide thicknesses and low nitride field, an additional current is shown to exist that is attributed to direct tunneling into traps in the nitride. The discharge of MNOS structures is briefly discussed and is shown to be due to a direct tunneling of charge carriers from traps in the nitride into the semiconductor.
136 citations