This paper deals with the positive identification by low-temperature photoluminescence microspectroscopy of the two spin states of the dicarbon antisites in 4H-SiC. The defects are created by high-dose electron irradiation at room temperature or by subsequent exposure to intense 325 nm radiation at... (Read more)

We carry out a comprehensive density-functional study of the vacancy-oxygen (VO) center in germanium using large H-terminated Ge clusters. The importance of a nonlinear core correction to account for the involvement of the 3d electrons in Ge-O bonds is discussed. We calculate the electrical... (Read more)

The authors have calculated that fluorine substituting for oxygen gives no gap states in HfO₂. This accounts for the good passivation of oxygen vacancies by F seen experimentally. Bonding arguments are used to account for why F may be the most effective passivant in ionic oxides such as... (Read more)

The optical excitation and thermal ionization energies of oxygen vacancies in m-HfO₂ are calculated using a non-local density functional theory with atomic basis sets and periodic supercell. The thermal ionization energies of negatively charged V^– and... (Read more)

The self-diffusion coefficient of zinc in ZnO is derived as a function of the chemical potential and Fermi level from first-principles calculations. Density functional calculations in combination with the climbing image-nudged elastic band method are used in order to determine migration barriers for... (Read more)

Two occupied native defect bands are experimentally detected in pure HfO₂. The density of states of band one in the middle of the band gap reduces drastically with the Al addition, while that of band two slightly above the valence-band maximum remains rather unaffected. We attribute the... (Read more)

Based on theoretical calculations, we find that at p+ polycrystalline silicon (poly-Si)/HfO₂ gates, Si interstitials are easily migrated from the electrode, forming Hf–Si bonds with a charge transfer to the electrode, and the resulting interface dipole raises the Fermi level... (Read more)

Nitrogen is known to reduce leakage currents and charge trapping in high-dielectric-constant gate oxides such as HfO₂. We show that this occurs because nitrogen, substituting for oxygen atoms next to oxygen vacancy sites, repels the occupied gap states due to the neutral and positively... (Read more)

Resonant interaction between longitudinal-optic (LO) phonons and electrons bound on shallow donors in GaN is studied using magnetoluminescence of neutral-donor bound excitons (D⁰X). The experiments were performed on high-quality freestanding GaN material and heteroepitaxial... (Read more)

Gradient-corrected density-functional calculations are used to determine the structure, stability, and diffusion of arsenic-interstitial and phosphorus-interstitial pairs in the positive, neutral, and negative charge states. For both cases, our calculations show that the neutral pair will be... (Read more)

Continuous-wave (cw) electron paramagnetic resonance (EPR) at both X-band and W-band frequencies, pulsed-EPR, and pulsed electron nuclear double resonance (ENDOR) were used to study phosphorus shallow donors in 3C-, 4H-, and 6H-SiC doped with phosphorus (P) during... (Read more)

We resolve the remarkably sharp bound exciton transitions of highly enriched ²⁸Si using a single-frequency laser and photoluminescence excitation spectroscopy, as well as photocurrent spectroscopy. Well-resolved doublets in the spectrum of the ³¹P donor reflect the hyperfine... (Read more)

We report Stark shift measurements for ¹²¹Sb donor electron spins in silicon using pulsed electron spin resonance. Interdigitated metal gates on a Sb-implanted ²⁸Si epilayer are used to apply the electric fields. Two quadratic Stark effects are resolved: a decrease of the... (Read more)

Electron paramagnetic resonance and ab initio supercell calculations suggest that the P6/P7 centers, which were previously assigned to the photoexcited triplet states of the carbon vacancy-antisite pairs in the double positive charge state, are related to the triplet ground... (Read more)

Oxygen vacancy in cubic HfO₂ was investigated using first-principles calculation based on density functional theory and generalized gradient approximation. Five different charge states (V⁺⁺, V⁺, V⁰, V^–, and... (Read more)

The atomistic effects of N atoms on the leakage current through HfO₂ high-k gate dielectrics have been studied from first-principles calculations within the framework of a generalized gradient approximation (GGA). It has been found that the intrinsic effects of N atoms drastically... (Read more)

Using ab initio density-functional total energy and molecular-dynamics simulations, we study the effects of various forms of nitrogen postdeposition anneal (PDA) on the electric properties of hafnia in the context of its application as a gate dielectric in field-effect transistors. We... (Read more)

Process-induced defects are a serious issue for modern sub-micron Si LSIs. To characterize such defects, two different techniques are useful: electrically detected magnetic resonance (EDMR) and transmission electron microscope (TEM), which can detect small (point) and extended defects, respectively. We applied EDMR and TEM to the issue of defect-induced leakage currents in dynamic-random-access memory (DRAM) cells. For our DRAM samples (a 0.25- μm-rule series), although TEM showed no extended defects, EDMR successfully detected two types of point defects: V₂+O x (Si divacancy-oxygen complexes) and larger Si vacancies (at least larger than V₆). We confirmed that these defects are the source of DRAM leakage currents. The observed defects were formed by ion implantation processes, but were more thermally stable than those in bulk Si crystals. The origins of this enhanced stability are attributed to the presence of oxygen atoms and a strong mechanical strain in LSIs. To clarify the origin of the complicated strain in LSI structures, we can directly measure the local-strain distribution in DRAM samples by means of convergent-beam electron diffraction (CBED) using TEM, which provides us with a valuable hint for understanding the formation mechanism of process-induced defects. (Read more)

Shallow N donors in n-type 4H-SiC were studied by electron paramagnetic resonance (EPR) and electron nuclear double resonance (ENDOR). For the N donor at the cubic site (N_k) in 4H-SiC, the hyperfine (hf) constants of the interaction with the nearest-neighbor... (Read more)

We report the observation of a paramagnetic interface defect in thermally oxidized porous n-type doped 4H–SiC/SiO₂. Based on its axial symmetry and resolved hyperfine interactions it is attributed to an sp³ carbon dangling bond center situated... (Read more)

We used electrically detected magnetic resonance to study the microscopic structure of ion-implantation-induced point defects that remained in large-scale Si integrated circuits (Si LSIs). Two types of defects were detected in the source/drain (n⁺-type) region of... (Read more)

Spin-lattice relaxation time (T₁) and phase memory time (T_M) of shallow donors in 3C-, 4H- and 6H-SiC have been measured in time domain by using pulsed EPR technique. The temperature dependence of T₁ suggests that the Orbach process should be frozen at relatively high temperatures. Shallow donors in SiC are promising in attaining a sufficiently long phase memory time at temperatures much higher than Si:P. (Read more)

Previous calculations on n-type doping of diamond by P and S predicted that S has a shallower level and a higher solubility than P. Our first-principles calculations show that the opposite is true: Phosphorus impurity in diamond gives rise to a shallower donor level, and has a higher bulk solid... (Read more)

The diffusion and reactions of hydrogenous species generated by single-pulsed F₂ laser photolysis of SiO-H bond in SiO₂ glass were studied in situ between 10 and 330 K. Experimental evidence indicates that atomic hydrogen (H⁰) becomes mobile even at temperatures as... (Read more)

We propose a network rebonding model for light-induced metastability in amorphous silicon, involving bonding rearrangements of silicon and hydrogen atoms. Nonradiative recombination breaks weak silicon bonds and generates dangling bond?floating bond pairs, with very low activation energies. The... (Read more)

We show that Cat-CVD silicon nitride films contain more than 1019 cm−3 nitrogen-bonded Si dangling bonds, similarly to the case for conventional CVD films. However, the charge-trapping behavior of the Cat-CVD films is found to be quite different, in spite of the same origin for the dominant... (Read more)

Electron-paramagnetic-resonance (EPR) studies in radiation damaged diamond enriched to 5% ¹³C have resulted in the identification of the nearest-neighbor divacancy center. It is the isotopic enrichment, and consequent observation of ¹³C hyperfine lines, that has permitted the... (Read more)

Hydrogen-related defects in oxygen-deficient silica, representing the material of a thermal gate oxide, are analyzed using first-principles calculations. Energetics and charge-state levels of oxygen vacancies, hydrogen, and their complexes in the silica framework are mapped out. The neutral hydrogen... (Read more)

Electron paramagnetic resonance measurements on float-zone silicon implanted with protons at ?50 K followed by heating to room temperature have revealed two signals S1_a and S1_b belonging to the S1 group of signals. S1_a and S1_b both originate from defects... (Read more)

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We report the observation of orthorhombic Au-Li and Pt-Li pairs in Si using EPR and ENDOR techniques and also MCDA spectroscopy. The EPR spectra alone could be mistaken as being due to orthorhombic isolated point defects and ENDOR is required to detect the Li partner of the pair. Comparison of the... (Read more)

Deep levels in vanadium-doped n- and p-type silicon have been investigated using deep level transient spectroscopy (DLTS) and concentration profile measurements. The DLTS measurement reveals two electron traps of E_C−0.20 eV and... (Read more)

The behavior of hydrogen in crystalline silicon is examined with state-of-the-art theoretical techniques, based on the pseudopotential-density-functional method in a supercell geometry. Stable sites, migration paths, and barriers for different charge states are explored and displayed in total-energy... (Read more)

The electron-nuclear double-resonance spectra of interstitial ⁴⁷Ti⁺ and ⁴⁹Ti⁺ in silicon have been measured at 4.2 K. Spin Hamiltonians for these systems were determined and had to include hyperfine contributions of the type S³I and... (Read more)

Experimental results are presented which identify the following chemical reaction as being responsible for compensation of shallow-acceptor impurities when single-crystal silicon is exposed to monatomic hydrogen: A^-+h⁺+H⁰↔(AH)⁰, where A^-... (Read more)

The dynamic process due to electron jumping among three states with different sp hybrid directions in the quasitetrahedral P⁴⁺ center [PO₄]⁰ in a-quartz has been investigated by 10-GHz electron paramagnetic resonance, over the temperature range 40 to 400 K. The relative populations (mole fractions ƒ_І and ƒ_ІІ) of the ground state P(І) and two degenerate thermally excited states P(ІІ) were determined from the measured EPR absorption line intensity ratios and from the line positions of the averaged state P(A), respectively, in the slow and fast kinetic regions. The temperature dependence of the mole fractions has been explained by considering vibrational sublevels in the potential well describing each state. The jump rate was also obtained, via EPR absorption line-width analysis based on the Bloch equations, in both the slow and the fast regions. The characteristic parameters of the dynamic process, Le., energy separation and vibrational sublevels of the ground and excited states, and barrier height between these, have been determined. (Read more)

A review is given on the diffusion, solubility and electrical activity of 3d transition metals in silicon. Transition elements (especially, Cr, Mn, Fe, Co, Ni, and Cu) diffuse interstitially and stay in the interstitial site in thermal equilibrium at the diffusion temperature. The parameters of the liquidus curves are identical for the Si:Ti — Si:Ni melts, indicating comparable silicon-metal interaction for all these elements. Only Cr, Mn, and Fe could be identified in undisturbed interstitial sites after quenching, the others precipitated or formed complexes. The 3d elements can be divided into two groups according to the respective enthalpy of formation of the solid solution. The distinction can arise from different charge states of these impurities at the diffusion temperature. For the interstitial 3d atoms remaining after quenching, reliable energy levels are established from the literature and compared with recent calculations. (Read more)

Dynamic averaging due to electron jumping among three states with different sp hybrid directions in the P⁴⁺ center [PO₄]⁰ in α-quartz has been studied by single-crystal electron paramagnetic resonance. The spin-Hamiltonian matrices g and A_slp for low temperature (i.e., C140 K) spectra P(І) and P(Ⅱ) and for high temperature spectrum P(A) are reported. For each crystal site, the line positions of P(A) agree well with those derived from the matrices measured for the three states. i.e., with weighted averages including P(І) and the two symmetry-related P(Ⅱ) spectra. (Read more)

This paper deals with an electron-paramagnetic-resonance study of the Si-B3 center, which was first reported by Daly. The Si-B3 center is a secondary defect which forms upon annealing between 50 and 175?C in irradiated boron-doped silicon and is stable up to ?500?C. Our studies indicate that the... (Read more)

EPR studies of silicon irradiated at 20.4 K and 4.2 K by 1.5 MeV and 46 MeV electrons are described. In 46 MeV irradiations the dominant defects formed appear to be divavancies and other multiple defect aggregates which liberate vacancies throughout the anneal to room temperature as they reorder, recombine, etc. For 1.5 MeV irradiations group III atoms play a vital role in p- and n-type materials in trapping interstitials and stabilizing damage. Carbon and oxygen are not effective interstitial traps at these temperatures. Evidence of limited vacancy migration during irradiation is also cited. Two distinct excited configurations of vacancy-oxygen pairs are identified as precursors to A-centre formation in n-type silicon. The kinetics for their conversion to A-centres depends strongly upon the Fermi level as does the isolated vacancy migration energy whhich is measured to be 0.18 ± 0.02 eV for the V^＝ charge state. The vacancy has four charge states, V^＋, V⁰, V^－ and V^＝. Kinetics for hole release from V^＋ reveals an activation barrier of 0.057 eV. The concentration of V^＋ at 20.4 K in boron-doped material indicates the corresponding donor level even closer to the band edge, approximately E_V ＋ 0.039 eV. Jahn-Teller energies for V⁰, V^＋, and V^－ are estimated from stress-alignment studies and confirmed to be large. Kinetics studies for reorientation from one Jahn-Teller distortion to another are also described for each charge state.