We utilize a very sensitive electron spin resonance technique called spin-dependent tunneling to identify defect centers involved in the negative bias temperature instability in plasma-nitrided p-channel metal-oxide-silicon field-effect transistors. The defect's ²⁹Si hyperfine... (Read more)

Secondary ion mass spectrometry and photoluminescence are employed to evaluate the origin and efficiency of hydrogen passivation of nitrogen in GaNAs and GaNP. The hydrogen profiles are found to closely follow the N distributions, providing unambiguous evidence for their preferential binding as the... (Read more)

We use ab initio methods to calculate the magnetic properties of vacancies in a graphitic boron nitride sheet (g-BN). By applying a full spin-polarized description to the system, we demonstrate that the nitrogen vacancy (V_N) or the boron vacancy (V_B)... (Read more)

We use positron annihilation spectroscopy to study 2 MeV ⁴He⁺-irradiated InN grown by molecular-beam epitaxy and GaN grown by metal-organic chemical-vapor deposition. In GaN, the Ga vacancies act as important compensating centers in the irradiated material, introduced at a... (Read more)

Nitrogen substitution of oxygen ions in cubic zirconia was studied theoretically at density functional level. Nitrogen contents of 12.5 and 3.1% were studied with Zr₈O_16−mN₂ and Zr₃₂O_64−mN₂ supercells. For... (Read more)

Silicon carbide nanotubes have a great potential for biological applications. It is of interest to explore the electronic properties of these nanotubes, and how those are modified in the presence of impurities. Hydrogen is a common impurity that can appear during the growth of silicon carbide... (Read more)

Detailed studies of mechanisms for hydrogen dissociative adsorption and diffusion on pure and nitrogen-doped (8, 0) carbon nanotubes are carried out using the first-principles density functional theory method. (1) For pure carbon nanotubes, we have identified the energetically most favorable... (Read more)

First principles calculations based on gradient corrected density functional theory have been carried out to study the magnetic coupling between Mn atoms in pure and carbon doped Ga_1−xMn_xN thin films. We show that the ground state of Mn-doped GaN (100) thin... (Read more)

By applying a new technique for dynamic nuclear polarization involving simultaneous excitation of electronic and nuclear transitions, we have enhanced the nuclear polarization of the nitrogen nuclei in ¹⁵N@C₆₀ by a factor of 10³ at a fixed temperature of 3 K and a... (Read more)

An experimental demonstration of electrical detection of coherent spin motion of weakly coupled, localized electron spins in thin fullerene C₆₀ films at room temperature is presented. Pulsed electrically detected magnetic resonance experiments on vertical photocurrents through... (Read more)

Complexes formed by H and the isoelectronic impurity N in GaAs_1-yN_y alloys have been widely investigated because the significant effects of N on the GaAs properties and their passivation by H represent a unique tool for a defect engineering of semiconductors.... (Read more)

We describe a possible pathway to new magnetic materials with no conventional magnetic elements present. The substitution of nitrogen for oxygen in simple nonmagnetic oxides leads to holes in N 2p states which form local magnetic moments. Because of the very large Hund's rule coupling of... (Read more)

Unlike the Si-SiO₂ interface, the SiC-SiO₂ interface has large defect densities. Though nitridation has been shown to reduce the defect density, the effect of H remains an open issue. Here we combine experimental data and the results of first-principles calculations to... (Read more)

Al₂O₃ thin films were deposited by atomic layer deposition on HF-cleaned and NH₃ plasma-treated GaAs surfaces, respectively. The precursors used for Al₂O₃ films are trimethylaluminum and water. Effects of NH₃ plasma pretreatment on... (Read more)

The effects of HfSiO nitridation on charge trapping and long-term dielectric reliability are investigated. A comparison between decoupled plasma nitridation, annealing in NH₃, and no nitridation is made. It was found that thinner HfSiO layers show less trapped charge. Decoupled plasma... (Read more)

The authors report on the influence of nitrogen incorporation on vacancies in GaAs based superlattices. The samples were molecular beam epitaxy grown on p-type GaAs substrates with the superlattice structure consisting of ten periods of quantum well material separated by GaAs buffers. Three... (Read more)

Using density functional theory, the interaction of hydrogen with a nitrogen vacancy in -Si₃N₄ is investigated. A single H atom was found to be energetically favorable over non- and doubly protonated vacancies. The traps composed of excess silicon and hydrogen have negative... (Read more)

The effects of nitridation on open volumes in thin HfSiO_x films fabricated by metal-organic chemical vapor deposition were studied using monoenergetic positron beams. It was found that positrons were annihilated from the trapped state by open volumes that exist intrinsically in... (Read more)

The N incorporation characteristics on a 4H-SiC epitaxial layer were reinvestigated. It was found that the desorption process and thermally activated process are aspects of the N incorporation mechanism of 4H-SiC to which attention should be paid. This mechanism depends on both the rate-limiting... (Read more)

Using density-functional total energy calculations, we investigated N interstitial migration in GaN. Two migration paths were considered. The first path confines motion to a single c-plane of the lattice, while the second path involves movement both perpendicular and parallel to the... (Read more)

Nitrogen-doping effects in silicon crystal growth have been theoretically studied using thermodynamical simulation based on first-principles calculation results. The results show that the densities of various complexes are determined in the balance between the enthalpy effects and the entropy... (Read more)

It is generally believed that nitrogen transport in vitreous silica exclusively takes place in molecular form, although no evidence for this is found in the literature. Actually, an analysis of literature data of transport of nitrogen and noble gases in vitreous silica at 900 °C suggests it may... (Read more)

Outdiffusion profiles of nitrogen, produced by 900 °C annealing and monitored by secondary ion mass spectroscopy, clearly show that the nitrogen community consists of three noninteracting components. The A component (dominant at higher nitrogen concentration) is represented by a species... (Read more)

The effects of thermal annealing and codoped impurities including carbon, nitrogen, oxygen, and fluorine, on the occupation of erbium lattice locations in Si, have been investigated in detail. Ion channeling measurements indicate that ion-implanted Er can mainly occupy two distinct lattice locations... (Read more)

The elevated-temperature properties of the N vacancy in Mg-doped, p-type GaN containing H were modeled using atomic-configuration energies and phonon densities of states obtained with density-functional theory. This study encompassed both equilibrium thermodynamics and the rates of diffusion... (Read more)

In this work we perform a systematic study of the dissolution of a dislocation loop layer under the influence of inert SiO₂/Si and nitrogen-rich SiO₂/Si interfaces. The composition of the dislocation loop layer was just after its formation 10%–20% Frank dislocation loops... (Read more)

High-efficiency visible light emission in N-and-B-doped 6H-SiC epilayers was observed in photoluminescence measurements at room temperature. The orange-yellow light emission due to the recombination of donor-acceptor pairs (DAPs) has a broad spectrum with a peak wavelength of 576 nm and a... (Read more)

The impact of nitridation on open volumes in thin HfSiO_x films fabricated on Si substrates by atomic layer deposition was studied using monoenergetic positron beams. For HfSiO_x, positrons were found to annihilate from the trapped state due to open volumes which... (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)

Hexagonal SiC is either co-implanted with silicon (Si⁺), carbon (C⁺), or neon (Ne⁺) ions along with nitrogen (N⁺) ions or irradiated with electrons (e⁻) of 200 keV energy. During the subsequent annealing step at temperatures above 1450 ... (Read more)

The electrical resistivity of 4H-SiC doped with nitrogen is analyzed in the temperature range 10–700 K for nitrogen concentrations between 3.5×10¹⁵ and 5×10¹⁹ cm⁻³. For the highest doped samples, a good agreement is found between the... (Read more)

We investigate transport properties of ultrananocrystalline diamond films for a broad range of temperatures. Addition of nitrogen during plasma-assisted growth increases the conductivity of ultrananocrystalline diamond films by several orders of magnitude. We show that films produced at low... (Read more)

We calculate the exchange interaction parameters of a classical Heisenberg Hamiltonian for Mn-doped ZnO (Mn concentration between 5% and 20%) by an ab initio Korringa-Kohn-Rostoker coherent-potential-approximation method in the framework of density functional theory. A weak antiferromagnetic... (Read more)

Adsorption of gold atoms and clusters (N=6) on a graphite (0001) surface with defects has been studied using density functional theory. In addition to perfect graphite (0001), three types of surface defects have been considered: a surface vacancy (hole), a pyridinelike defect comprising three... (Read more)

We report on room-temperature coherent manipulation of the spin of a single nitrogen-vacancy center in diamond and a study of its coherence as a function of magnetic field. We use magnetic resonance to induce Rabi nutations and apply a Hahn spin echo to remove the effect of low-frequency dephasing.... (Read more)

An extended vibronic spectrum (up to six phonon replicas) has been measured by low temperature cathodoluminescence in pure c-BN microcrystalline samples obtained by high temperature high pressure method. The zero phonon line, found at 3.573 eV, should be connected to a center identified... (Read more)

The role of various types of defects in establishing the magnetic properties of the C₆₀-based polymers and the single-wall carbon nanotubes is investigated. Comparing the role of carbon vacancies, and that of substitutional impurity atoms X (X=N, B, O, Si, P, and S) in... (Read more)

Experimental studies of Zn_1−xCo_xO as thin films or nanocrystals have found ferromagnetism and Curie temperatures above room temperature and that p- or n-type doping of Zn_1−xCo_xO can change its magnetic... (Read more)

Symmetry considerations are used in presenting a model of the electronic structure and the associated dynamics of the nitrogen-vacancy center in diamond. The model accounts for the occurrence of optically induced spin polarization, for the change of emission level with spin polarization and for new... (Read more)

High-quality single crystals of ZnO in the as-grown and N⁺ ion-implanted states have been investigated using a combination of three experimental techniques—namely, positron lifetime/slow positron implantation spectroscopy accompanied by theoretical calculations of the positron... (Read more)

We have studied bound exciton states of isoelectronic centers of nitrogen-doped GaAs by photoluminescence (PL) spectroscopy. The nitrogen doping has been performed in an atomically controlled way using the (3×3) nitrogen stable surface on GaAs(001), which has succeeded in forming a series of... (Read more)

High resolution photoluminescence spectroscopy on heavily doped GaAs:N reveals the existence of excitons bound to a nitrogen cluster. The observed transitions are exceedingly sharp, similar to those observed for excitons bound to nitrogen pairs in high quality GaAs with the narrowest transition... (Read more)

Silicon carbide nanotubes have a great potential for application in chemical sensors in harsh environment or in biological sensors. It is of interest to explore the electronic properties of these nanotubes, and how those are modified in the presence of impurities. It is well known that nitrogen and... (Read more)

Using microphotoluminescence (µ-PL), in dilute N GaAs_1–xN_x alloys, we observe a PL band far above the bandgap E₀ with its peak energy following the so-called E₊ transition, but with contribution from perturbed... (Read more)

An optically detected magnetic resonance (ODMR) study of Ga(Al)NAs alloys grown by molecular beam epitaxy on GaAs substrates is presented. A number of grown-in defects were observed which act as nonradiative recombination centers. A detailed analysis of experimental data using a spin Hamiltonian... (Read more)

Silicon oxynitride films were deposited using a plasma-enhanced chemical vapor deposition process. The bond configurations of the constituent atoms in the deposited film were analyzed using x-ray photoelectron spectroscopy. Analysis of the Si 2p spectra showed the presence of... (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)

Interface defects related to negative-bias temperature instability (NBTI) in an ultrathin plasma-nitrided SiON/ Si<100> system were characterized by using conductance–frequency measurements, electron-spin resonance measure- ments, and synchrotron radiation X-ray photoelectron spectroscopy. It was confirmed that NBTI is reduced by using D₂-annealing instead of the usual H₂-annealing. Interfacial Si dangling bonds (P_b1 and P_b0 centers) were detected in a sample subjected to negative-bias temperature stress (NBTS). Although we suggest that NBTS also generates non-Pb defects, it does not seem to generate nitrogen dangling bonds. These results show that NBTI of the plasma-nitrided SiON/Si system is predominantly due to P_b depassivation. Plasma nitridation was also found to increase the P_b1/P_b0 density ratio, modify the P_b1 defect structure, and increase the latent interface trap density by generating Si suboxides at the interface. These changes are likely to be the causes of NBTI in ultrathin plasma-nitrided SiON/Si systems. (Read more)

Interfacial defect structures of NO-nitride oxide on Si(100) were characterized by electron spin resonance spectroscopy. We confirmed that the effective g values of the P_b1 center are affected by interfacial nitridation even at a small nitrogen concentration of 5 at. %, while those of the P_b0 center proved to be unchanged. We observed that the shifted P_b1 line appeared gradually with interfacial nitrogen concentration, which suggests that the nitrogen-induced modified structure substitutes for the original P_b1 structure. Angular variations of the shifted P_b1 lines were also significantly different from those of pure oxide. Based on our analysis, we attributed the g value shift of the P_b1 center to dangling bond tilting, caused by the displacement of nearest-neighbor Si atoms. (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)

Combining efficient density-functional based tight-binding molecular dynamics with ab initio calculations, we show that despite higher formation energies the incorporation of phosphorus at the carbon sublattice is favored by kinetic effects during the annealing processes. Based on the... (Read more)

We report the identification of the vacancy-hydrogen complex in single crystal diamond synthesized by chemical vapor deposition. The S = 1 defect is observed by electron paramagnetic resonance in the negative charge state. The hydrogen atom is bonded to one of the carbon atoms neighboring the... (Read more)

Interface defects generated by negative-bias temperature stress (NBTS) in an ultrathin plasma- nitrided SiON/Si(100) system were characterized by using D₂ annealing, conductance-frequency measurements, and electron-spin resonance measurements. D₂ annealing was shown to lower... (Read more)

Electron paramagnetic resonance (EPR) has been used to investigate molecular nitrogen and isolated nitrogen acceptors in single crystals of ZnO. These samples were grown by the seeded chemical vapor transport method with N₂ added to the gas stream. A five-line EPR spectrum is observed at... (Read more)

We present an overview of negative bias temperature instability (NBTI) commonly observed in p-channel metal–oxide–semiconductor field-effect transistors when stressed with negative gate voltages at elevated temperatures. We discuss the results of such stress on device and circuit... (Read more)

Hydrogen is well known to cause electrical passivation of lattice vacancies in semiconductors. This effect follows from the chemical passivation of the dangling bonds. Recently it was found that H in the carbon vacancy of SiC forms a three-center bond with two silicon neighbors in the vacancy, and... (Read more)

We propose a mechanism for the annealing of vacancy-related defects in SiC, based on ab initio total energy calculations. Our mechanism is based on the formation and migration of carbon and nitrogen split interstitials resulting in C_Si(N_C)_n or... (Read more)

The selection rules for transitions between the electronic levels of shallow donors in 4H-SiC in the dipole approximation are derived. The ionization energy of the shallow nitrogen donor (at hexagonal site) is determined to be 61.4±0.5 meV by analyzing the photothermal ionization and... (Read more)

First-principles calculations are carried out on models for the Z₁/Z₂ defects in 4H–SiC which are found in as-grown and irradiated n-type material. We show that an interstitial-nitrogen–interstitial-carbon defect is exceptionally thermally stable,... (Read more)

We report the identification of the nitrogen-vacancy-hydrogen complex in a freestanding nitrogen-doped isotopically engineered single crystal diamond synthesized by chemical vapor deposition. The hydrogen atom is located in the vacancy of a nearest-neighbor nitrogen-vacancy defect and appears to be... (Read more)

We apply positron annihilation spectroscopy to identify V_N–Mg_Ga complexes as native defects in Mg-doped GaN. These defects dissociate in postgrowth annealings at 500–800 °C. We conclude that V_N–Mg_Ga complexes contribute to... (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)

Two paramagnetic intrinsic defects P and ND1 have been studied in both C-rich n-type 4H-SiC and undoped semi-insulating (s.i.) 4H-SiC in the dark and under illumination of the s.i. sample with light at 140 and 37 GHz in the temperature interval from 4.2 to 77 K. Photo EPR and Hall effect... (Read more)

Recent results from studies of shallow donors, pseudodonors, and deep level defects in SiC are presented. The selection rules for transitions between the electronic levels of shallow donors in 4H–SiC in the dipole approximation are derived and the ionization energy for the N donor at... (Read more)

We used a density functional method to investigate the mechanism of negative-bias temperature instability (NBTI) and resultant structural changes of Si/SiO₂ and Si/SiO_xN_y interfaces. The reaction energies for the water- and hydrogen-originated... (Read more)

Photoinduced electron paramagnetic resonance studies performed on nominally semi-insulating, high purity 4H-SiC have revealed charge transfer from an intrinsic defect (ID) to both the shallow boron acceptor and nitrogen donor. At 4 K, incident photon energy between 1.0 and 1.7 eV produces an... (Read more)

Nitrogen acceptors are formed when undoped single crystals of zinc oxide (ZnO) grown by the chemical-vapor transport method are annealed in air or nitrogen atmosphere at temperatures between 600 and 900 °C. After an anneal, an induced near-edge absorption band causes the crystals to appear... (Read more)

Photosensitive electron paramagnetic resonance (EPR) investigations of unintentionally doped, semi-insulating (s.i.) 4H?SiC have been made at 37 GHz and 77 K including photoexcitation and photoquenching experiments. In the dark the EPR spectrum consists of a low intensity line due to boron on the... (Read more)

In this paper, we present high-frequency (95 GHz) pulsed electron paramagnetic resonance (EPR) and electron nuclear double resonance (ENDOR) measurements on the nitrogen (N) donor in 4H-SiC (k site) and 6H-SiC (h, k₁, and k₂ sites according to the accepted classification). From... (Read more)

We have used EPR and ODMR to study state-of-the-art bulk ZnO single crystals. Most of the samples are n-type; however, under certain conditions (e-irradiated or annealed), we observe a center due to residual nitrogen (g||=1.9953, g=1.9633 and Aiso=1.225 mT, Aaniso=0.864 mT). The N center is a... (Read more)

Comparisons are made between the carrier concentrations, ionization energies, and electron mobilities in 4H–SiC samples implanted with similar doses of nitrogen or phosphorus and annealed at 1300 or 1700 °C for 10 min in argon. The objective of the research is to determine which element may... (Read more)

Photothermal ionization spectroscopy (PTIS) measurements were carried out on a free-standing, high purity and high quality 4H–SiC epitaxial layer at various temperatures. The two step photothermal ionization process is clearly reflected in the temperature dependence of the photoconductivity.... (Read more)

Using deep-level transient spectroscopy, we studied defect energy levels and their annealing behavior in nitrogen-doped 6H-SiC epitaxial layers irradiated with 2-MeV electrons and implanted with 300-KeV deuterium or hydrogen at room temperature. Five levels located at E_c-0.34,... (Read more)

Isochronal annealing investigations in electron-irradiated 6H-SiC were correlated with temperature-dependent measurements of positron lifetime. It turned out that the positron trapping at temperatures up to 300 K was dominated by the trapping in shallow positron traps. These defects were already... (Read more)

Electron paramagnetic resonance (EPR) measurements of Si/SiO₂ systems began over 30 years ago. Most EPR studies of Si/SiO₂ systems have dealt with two families of defects: P_b centers and E centers. Several variants from each group have... (Read more)

Nitrogen donors in 6H-, 4H- and 3C-SiC were investigated using conventional electron paramagnetic resonance (EPR) and electron nuclear double resonance (ENDOR) and the experimental results are discussed. An attempt is presented to interpret the experimentally found large differences in hyperfine... (Read more)

Investigations of nitrogen donors in 6H-, 4H- and 3C-SiC using conventional electron paramagnetic resonance (EPR), electron nuclear double resonance (ENDOR) and optical detection of EPR and ENDOR as well as optical absorption and emission spectroscopy are reviewed and critically discussed. An... (Read more)

Gamma ray-induced decomposition of the binary mixtures of zirconium and thorium nitrates with 2.5, 5 and 10 mol% of V2O5, PbO, ThO2, ZrO2, and MnO2 has been studied at different doses up to 260 kGy. Radiation chemical yield G(NO2−)-values are enhanced by V2O5, PbO, and ThO2 but are decreased... (Read more)

Photoinduced O^– ions or V-type centers have been detected in ZnO following ultraviolet irradiation at –196°C. The EPR spectrum of the ions is characterized by g=2.021 and g = 2.0026. The concentration of O^– was greatly... (Read more)

An electron spin resonance study of the surface interaction of zinc oxide with oxygen, oxides of nitrogen (NO2, NO and N2O) and chlorine was made. Characteristic spectra obtained following adsorption of NO2 and NO were analyzed and attributed to rigidly adsorbed neutral molecules. Confirmation of... (Read more)

An ESR study of the interaction of nitrobenzene with nonstoichiometric ZnO surfaces was made. A 3-line spectrum with g values 1.9840, 2.0055 and 2.0225 was observed and was identified as due to nitrobenzene anion radicals strongly held to the surface. An unidentified signal at g = 2.0050 was left... (Read more)

By using the recently measured effective masses for n-type Si, m₁=0.98 m and m₂=0.19 m, approximate solutions of the resulting effective mass Schroedinger equation are obtained. The accuracy of the solutions was tested in the limiting cases where... (Read more)