A rich variety of optical centers with high energy local vibrational modes has been found in electron-irradiated 4H-SiC in both the as-irradiated and annealed states. These energies have been measured and the annealing dependence of the optical centers has been investigated by low-temperature... (Read more)

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)

The effect of open-core screw dislocations on photoluminescence in n-doped wurtzite GaN epilayer is studied computationally and compared with experimental data. A k•p Hamiltonian calculation domain is set up to contain a dipole of open-core screw dislocations, and its size... (Read more)

We present the results of an electron paramagnetic resonance study of homogeneous single phase Zn_1−xMn_xO thin films with Mn concentrations varying between x=0.07 and x=0.34. Our results show antiferromagnetic (AF) coupling in the entire... (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)

We have measured positron lifetime and Doppler broadening in highly As-doped silicon containing thermally generated V-As₃ defect complexes (vacancy is surrounded by three arsenic atoms). We observe positron detrapping from the V-As₃ defect complex and determine... (Read more)

The migration of monovacancies (V⁰) and self-interstitials (I) has been observed in ion-implanted low-doped float-zone silicon by variable-energy positron annihilation spectroscopy. V⁰ and I were created by the in situ implantation of ~20 keV... (Read more)

The doping characteristics and carrier transport in a GaAs p-n junction were visualized with a ~10 nm spatial resolution, using light-modulated scanning tunneling spectroscopy. The dynamics of minority carriers under operating conditions, such as recombination, diffusion, and electric... (Read more)

Defect formation during Pd and Pt germanidation of n-type germanium, using rapid thermal annealing in the range of 300–500 °C, is investigated by deep level transient spectroscopy. Small concentrations of an electron trap at ~E_C−0.385 eV are found,... (Read more)

The authors have employed deep level transient spectroscopy to investigate the defects introduced in n-type Ge during 160 keV indium (In) ion implantation. Our results show that In implantation introduces three prominent electron traps with energy levels at... (Read more)

The low field Hall mobility of electron in diamond was investigated from room temperature to 873 K, both experimentally and theoretically. The acoustic deformation potential for electron scattering is determined by fitting of theoretical calculations to experimental data for high quality {111}... (Read more)

Li-doped ZnO films were prepared by pulsed laser deposition. The carrier type could be controlled by adjusting the growth conditions. In an ionized oxygen atmosphere, p-type ZnO was achieved, with the hole concentration of 6.04×10¹⁷ cm^–3 at an optimal Li... (Read more)

The effects of dislocations and Si doping on the electrical properties of n-type GaN grown by metal organic chemical vapor deposition (MOCVD) are investigated. It is found that both electron mobility and carrier concentration are strongly influenced by edge dislocations. A moderate Si doping... (Read more)

Low pressure chemical vapor deposition of Si₃N₄ on oxidized Si (111) surfaces causes a change in the properties of the dominant interface defect, the P_b center, observed by electron paramagnetic resonance. The change in the signature of the... (Read more)

In this work, the formation of donors in n-type high resistivity magnetic Czochralski-grown silicon wafers, directly exposed to a hydrogen plasma, is investigated by a combination of capacitance-voltage (C-V) and deep level transient spectroscopy (DLTS) measurements.... (Read more)

As-grown InN is known to exhibit high unintentional n-type conductivity. Hall measurements from a range of high-quality single-crystalline epitaxially grown InN films reveal a dramatic reduction in the electron density (from low 10¹⁹ to low 10¹⁷ cm^–3)... (Read more)

We have investigated by deep level transient spectroscopy the hole and electron trap defects introduced in n-type Ge during electron beam deposition (EBD) of Pd Schottky contacts. We have also compared the properties of these defects with those introduced in the same material during... (Read more)

Cathodoluminescence (CL) and photoluminescence (PL) properties are studied on neodymium (Nd)- and dysprosium (Dy)-ion-implanted 4H–SiC. No appreciable CL and PL can be observed for all as-implanted samples. Strong visible CL due to Nd³⁺ and Dy³⁺ is observed only after... (Read more)

Nickel-germanide Schottky barriers have been made on n-type germanium and evaluated by deep level transient spectroscopy in order to detect possible metal indiffusion during the 30 s rapid thermal annealing (RTA) employed for the germanidation. It is shown that while no electron traps have... (Read more)

We report low-frequency charge noise measurement on silicon substrates with different phosphorus doping densities. The measurements are performed with aluminum single electron transistors (SETs) at millikelvin temperatures where the substrates are in the insulating regime. By measuring the SET... (Read more)

The effect of forming gas and vacuum annealing on the concentration of carbon dangling bond (P_bC) centers at 3C- and 4H-SiC/SiO₂ interfaces has been studied by electron paramagnetic resonance (EPR) spectroscopy. Our results show efficient passivation at 400 °C and... (Read more)

Low-injection minority carrier lifetimes (MCLs) and deep trap spectra have been investigated in n^– 4H-SiC epilayers of varying layer thicknesses, in order to enable the separation of bulk lifetimes from surface recombination effects. From the linear dependence of the inverse... (Read more)

Deep levels in n-type 4H-SiC epilayers have been investigated by deep level transient spectroscopy (DLTS). The Z_1/2 and EH_6/7 centers are dominant in as-grown samples. After electron irradiation at 116 keV, by which only carbon atoms may be displaced, the... (Read more)

Temperature dependent Hall effect (TDH), low temperature photoluminescence (LTPL), secondary ion mass spectrometry (SIMS), optical admittance spectroscopy (OAS), and thermally stimulated current (TSC) measurements have been made on 6H-SiC grown by the physical vapor transport technique... (Read more)

The impact of threading dislocation density on Ni/n-GaN Schottky barrier diode characteristics is investigated using forward biased current-voltage-temperature (I-V-T) and internal photoemission (IPE) measurements. Nominally, identical metal-organic chemical vapor... (Read more)

Isothermal deep-level transient spectroscopy (DLTS) with a single pulse has been used to study the transformation behavior of hydrogen-related metastable defects labeled EM1 (E_c–0.28 eV) and EM2 (E_c–0.37 eV), which are observed in... (Read more)

Sulfur ions are implanted into 6H-, 4H-, and 3C-SiC. Admittance and double correlated deep level transient spectroscopy investigations reveal that S atoms form double donors in SiC, which reside on lattice sites. The number of double donors observed corresponds to the number of... (Read more)

Low-temperature photoluminescence spectroscopy has revealed a series of features labeled S₁, S₂, S₃ in n-type 6H-SiC after neutron and electron irradiation. Thermal annealing studies showed that the defects S₁,... (Read more)

In this paper, the formation and evolution of defects induced by ion irradiation with 1 MeV Si⁺ ions in Ni₂Si/4H–SiC Schottky diodes were studied and correlated with the electrical properties of the contacts. The current-voltage characteristics of the contacts... (Read more)

Only a few years ago, an account of degradation of silicon carbide high-voltage p-i-n diodes was presented at the European Conference on Silicon Carbide and Related Compounds (Kloster Banz, Germany, 2000). This report was followed by the intense effort of multiple groups... (Read more)

Computational techniques are key predictive tools in the drive to engineer semiconductive materials. Diamond, intrinsically a wide band-gap insulator, can be made to semiconduct n-type by doping with phosphorus. However, the relatively deep level at E_c−0.6 eV... (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 investigate transport in phosphorus-doped buried-channel metal-oxide-semiconductor field-effect transistors at temperatures between 10 and 295 K. We focus on transistors with phosphorus donor concentrations higher than those previously studied, where we expect conduction to rely on donor... (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)

Two-dimensional electron systems fabricated from a single layer of P-donors have been lithographically confined to nanometer scale in lateral directions. The electronic transport of such quasi-one-dimensional systems with and without a perpendicular magnetic field was characterized at cryogenic... (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)

A model of arsenic clustering in silicon is proposed and analyzed. The main feature of the proposed model is the assumption that negatively charged arsenic complexes play a dominant role in the clustering process. To confirm this assumption, electron density and concentration of impurity atoms... (Read more)

We report on the static magnetic field dependence of the random telegraph signal in a submicrometer silicon n-metal-oxide-semiconductor field-effect transistor. Using intense magnetic fields and low temperatures, we find that the characteristic time ratio changes by three orders of magnitude... (Read more)

Recent ab initio calculations [Mattausch et al., Phys. Rev. B 70, 235211 (2004)] of carbon clusters in SiC reveal a possible connection between the tricarbon antisite (C₃)_Si and the U photoluminescence center in 6H-SiC [Evans et al., Phys. Rev. B 66, 35204... (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)

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)

Phosphorus shallow donors having the symmetry lower than Td are studied by pulsed EPR. In diamond:P and 3C–SiC:P, the symmetry is lowered to D2d and the density of the donor wave function on the phosphorus atom exhibits a predominant p-character. In 4H–SiC:P with the site symmetry of... (Read more)

ZnO substrate crystals from two different sources, and epitaxial layers have been studied by SEM, AFM, photoluminescence and EPR. Although fabricated by the same growth principle, i.e. the hydrothermal technique, the substrates differ in terms of purity and structural quality. In the PL spectra of... (Read more)

Zinc oxide crystals grown by the seeded chemical vapor transport method have been annealed in zinc vapor at 1100 °C for 30 min. These thermochemical reduction treatments produce a deep red coloration in the crystals and increase their n-type electrical conductivity. Electron paramagnetic... (Read more)

Electron-positron momentum distributions associated with vacancy defects in 6H-SiC after irradiation with 2-MeV electrons and annealing at 1000 °C have been studied using angular correlation of annihilation radiation measurements. It was confirmed that the above vacancy defects have... (Read more)

Low temperature annealing of electron irradiation-induced deep levels in 4H-SiC is reported. The major deep level transient spectroscopy peak S2 associated with the energy level at E_c–0.39 eV disappears in the temperature range 360–400 K, and some rearrangement... (Read more)

N-type epitaxial 4H-SiC layers grown by hot-wall chemical vapor deposition were investigated with regard to deep centers by capacitance-voltage measurements and deep level transient spectroscopy (DLTS). The DLTS spectra revealed that the concentrations of deep centers were reduced by one... (Read more)

We show direct evidence, obtained by positron annihilation spectroscopy, for the complexing of fluorine with vacancies in silicon. Both float zone and Czochralski silicon wafers were implanted with 30 keV fluorine ions to a fluence of 2×10¹⁴ ions/cm², and studied in the... (Read more)

We utilize spin-dependent recombination (SDR) to observe deep level trap defects at or very near the interface of 6H silicon carbide and the SiO₂ gate dielectric in SiC metal-oxide-semiconductor field effect transistors. The SDR response is strongly correlated to SiC/SiO₂... (Read more)

Epitaxial 4H-SiC n-type layers implanted at room temperature with a low fluence of mega-electron-volt protons have been measured by deep level transient spectroscopy (DLTS). The proton fluence of 1×10¹² cm^–2 creates an estimated initial concentration of... (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)

Combining electron paramagnetic resonance measurements with ab initio calculations, we identify the V_CC_Si(Si_CC_Si) complex as a second annealing product of the silicon vacancy via an analysis of resolved carbon hyperfine interactions and of... (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)

Optical excitation at 1.7 K with 364-nm laser light produces partial annealing recovery of the damage produced in GaN by 2.5-MeV electron irradiation in situ at 4.2 K. Observed is a reduction in the irradiation-produced 0.95-eV photoluminescence (PL) band, recovery in the visible... (Read more)

Irradiation of GaN by 2.5-MeV electrons in situ at 4.2 K produces a broad photoluminescence (PL) band centered at 0.95 eV. Optical detection of electron paramagnetic resonance (ODEPR) in the band reveals two very similar, but distinct, signals, L5 and L6, which we identify as interstitial... (Read more)

We report results of electron paramagnetic resonance, magnetization, and optical absorption studies of bulk GaN crystals doped with Mn and, for some samples, codoped with Mg acceptor. The experiments performed show that the charge state of the Mn ion in GaN depends on the Fermi level position in the... (Read more)

The driving force of stacking-fault expansion in SiC p–i–n diodes was investigated using optical emission microscopy and transmission electron microscopy. The stacking-fault expansion and properties of the partial dislocations were inconsistent with any stress as 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)

N-type 6H–SiC samples irradiated with electrons having energies of E_e = 0.2, 0.3, 0.5, and 1.7 were studied by deep level transient technique. No deep level was detected at below 0.2 MeV irradiation energy while for E_e0.3 MeV,... (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)

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)

ZnO nanocrystals with diameters ranging from 4 to 50 nm were prepared via a wet chemical method and post-growth annealing treatments. The electron paramagnetic resonance (EPR) spectra of the nanocrystals show the resonance of electron centers with g-value close to that of the shallow donors in bulk... (Read more)

Phosphorus ion implantations of 6H-SiC in the mean phosphorus concentration of the implanted layer of 1 × 1018 cm−3 were performed both at multi-fold energy between 9 and 21 MeV and at 340 keV. In the high-energy implantations at room temperature, 400, 800 and 1200 °C and in the 340... (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)

Electron-paramagnetic-resonance (EPR) and electron-spin-echo (ESE) studies have been performed that show that isolated V_Si^-, V_Si⁰, and V_C vacancies are the dominant intrinsic paramagnetic defects in SiC treated by room-temperature neutron... (Read more)

A Comment on the Letter by A. A. Rempel et al., Phys. Rev. Lett. 89, 185501 (2002). The authors of the Letter offer a Reply.... (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)

The effect of vacancies on the behavior of F in crystalline Si has been elucidated experimentally for the first time. With positron annihilation spectroscopy and secondary ion mass spectroscopy, we find that F retards recombination between vacancies (V) and interstitials (I) because V and I trap F to form complexes. F diffuses in the V-rich region via a vacancy mechanism with an activation energy of 2.12±0.08 eV. After a long annealing time at 700ºC, F precipitates have been observed by cross-section transmission electron microscopy which are developed from the V-type defects around the implantation range and the I-type defects at the end of range. (Read more)

The thermal stability and annealing kinetics of a bistable defect, recently reported by Martin (Master Thesis, KTH/ELE/FTE/2003-1) employing deep level transient spectroscopy and labelled the M-centre, has been studied using n-type epitaxially grown 4H-SiC layers implanted with 2.5 MeV protons to a... (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)

Optical injection of electron-hole pairs in 3–5 nm thick layers of SiO₂, Al₂O₃, ZrO₂ and their stacks on (100)Si is found to result in positive oxide charging, suggesting trapping of holes. In thin layers of the high-permittivity metal oxides... (Read more)

We will highlight our recent work on the properties of residual defects and dopants in GaN heteroepitaxial layers and on the nature of recombination from InGaN single quantum well (SQW) light emitting diodes (LEDs) through magnetic resonance techniques. Electron paramagnetic resonance (EPR) and... (Read more)

The silicon vacancy in its neutral charge state (V_Si) has been unambiguously identified in 4H- and 6H-SiC. This was achieved by observation of ligand hyperfine interaction with the four carbon atoms in the nearest-neighbor shell and the twelve silicon atoms in the next-nearest-neighbor... (Read more)

Three broad overlapping photoluminescence bands, centered at ?1.75?eV (red), ?2.2?eV (yellow), and ?2.33?eV (green), are observed in low-dislocation-content GaN grown by the hydride vapor-phase epitaxy method. Optical detection of electron paramagnetic resonance (ODEPR) studies reveal that each is... (Read more)

The identification of atomic defects in solids is of pivotal interest for understanding atomistic processes and solid state properties. Here we report on the exemplary identification of vacancies on each of the two sublattices of SiC by making use of (i)?electron irradiation, (ii)?measurements of... (Read more)

Electron paramagnetic resonance and Hall measurements show consistently the presence of two donors ( D1 and D2) in state-of-the-art, nominally undoped ZnO single crystals. Using electron nuclear double resonance it is found that D1 shows hyperfine interaction with more than 50 shells of surrounding... (Read more)

Annealing behavior of vacancies and the Z_1/2 levels in n-type 4H–SiC epilayers after 2 MeV electron irradiation has been studied using positron annihilation and deep-level transient spectroscopy. Isochronal annealing studies indicate that silicon vacancy-related defects... (Read more)

In our letter, we suggested that the reduction of interface state density (D_it) is caused by the termination of Si and C dangling bonds with hydrogen.¹ In a comment on our letter,² Afanas'ev et al. argue that the D_it originates from carbon clusters at the... (Read more)

The annealing behavior of defects in n-type 6H SiC epilayers irradiated with 2 MeV electrons have been studied using positron annihilation and deep level transient spectroscopy. Vacancy-type defects are annealed at 500–700 °C and 1200–1400 °C. From the analysis of... (Read more)

We investigated radiation-induced defects in neutron-irradiated and subsequently annealed 6H-silicon carbide (SiC) with electron paramagnetic resonance (EPR), the magnetic circular dichroism of the absorption (MCDA), and MCDA-detected EPR (MCDA-EPR). In samples annealed beyond the annealing... (Read more)

Experimental studies of size-related effects in silicon nanocrystals are reported. We present investigations carried out on nanocrystals prepared from single-crystal Si:P wafer by ball milling. The average final grain dimension varied depending on the way of preparation in the range between 70 and... (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)

Mn_i4⁰ clusters were investigated by electron paramagnetic resonance in silicon specimens with initial doping concentrations between 1.5?10¹⁵?P cm^-3 and 5?10¹⁶?B cm^-3. In n-type samples and in intrinsic samples, we obtained the EPR... (Read more)

Electron spin resonance experiments were performed on Si-doped wurtzite and zinc-blende GaN and Si-doped wurtzite Al_xGa_1-xN alloys with x=0.15, 0.32, 0.52, 0.75, and 1. For zinc-blende GaN, an isotropic g factor of 1.9475 is found. The g tensors of the silicon effective mass... (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)