The recently developed effective Schrödinger-like Hamiltonian equation (EHA) in a model space of near-degenerate nonrelativistic two-component spinors is applied to the relativistic energy corrections at first, second, and third order of $c^{\text{−2}}$ within the framework of relativistic direct perturbation theory (DPT). The dominant singular part of the total relativistic correction is already recovered by the lowest-order effective Hamiltonian in the spirit of degenerate perturbation theory, while the perturbative expansion needs to account for only the small remaining part. Numerical results for groups of excited potential curves of the one-electron ${\mathrm{H}}_{\mathrm{2}}^{\mathrm{+}}$ -like quasimolecule ${\mathrm{Sn}}_{\mathrm{2}}^{\mathrm{99+}}$ are presented and discussed. In general the most efficient approach is first-order EHA-DPT for the set of states, followed by single-state DPT of higher orders.

State-of-the-art SIMS, XRR and AFM have been used to determine the effect of oxidation temperature on the inhomogeneity of chemical composition and density in nanometric SiO₂ films grown on n-type 4H-SiC by thermal oxidation in dry oxygen.

Parameters of electrically active defect centres in vanadium-doped 6H silicon carbide (6H-SiC:V) were investigated by means of the photoinduced transient spectroscopy (PITS) and modulated photocurrent (MPC) method. After a short description of the two techniques, experimental results are presented and briefly compared. Our aim is mainly to understand and explain these experimental results. In particular, in the PITS technique a shallow level seems to be at the origin of negative photoconductivity. Besides, in the same temperature range hole and electron levels can be detected at the same time. Finally, the detection of a given level seems to depend on the photon flux used to perform the PITS experiment. As far as the MPC experiment is concerned, it has put into evidence a very efficient shallow level. A numerical calculation was developed to simulate both experiments in order to understand the experimental results. By means of this simulation, we have explained all the phenomena observed experimentally in each technique and we propose a simple model for the distribution of electrically active defect centres in 6H-SiC:V crystals.

Laplace photoinduced transient spectroscopy has been applied to determine the electronic properties and concentrations of deep traps in high purity n-type silicon irradiated with high fluences of 23-MeV protons. From the temperature dependence of thermal emission rates of excess charge carriers obtained by the analysis of the photocurrent relaxation waveforms measured at temperatures of 30–320 K, eight deep traps with activation energies ranging from 255 to 559 meV have been resolved. The dependence of these trap’s concentrations on the proton fluence are demonstrated for the fluence values ranging from 1 × 10¹⁴ to 5 × 10¹⁵ n_eq/cm². In comparison to the previously reported results of theoretical and experimental studies on the electronic properties of small vacancy clusters in irradiated silicon, we tentatively attribute four detected traps with activation energies of 255, 367, 405, and 512 meV to the energy levels related to the 2−/− charge state changes of divacancy (V₂), trivacancy (V₃), tetravacancy (V₄), and pentavacancy (V₅), respectively. Simultaneously, we propose the attribution of four deep traps with higher activation energies of 415, 456, 526, and 559 meV to the energy levels related to the −/0 charge state changes of these small vacancy clusters, respectively.

The formation of intrinsic point defects in the N-sublattice of semi-insulating Mg-doped GaN crystals grown by the ammonothermal method (SI AT GaN:Mg) was investigated for the first time. The grown-in defects produced by the displacement of nitrogen atoms were experimentally observed as deep traps revealed by the Laplace transform photoinduced transient spectroscopy in the compensated p-type crystals with the Mg concentrations of 6 × 10¹⁸ and 2 × 10¹⁹ cm⁻³ and resistivities of ~10¹¹ Ωcm and ~10⁶ Ωcm, respectively. In both kinds of materials, three closely located traps with activation energies of 430, 450, and 460 meV were revealed. The traps, whose concentrations in the stronger-doped material were found to be significantly higher, are assigned to the (3+/+) and (2+/+) transition levels of nitrogen vacancies as well as to the (2+/+) level of nitrogen split interstitials, respectively. In the material with the lower Mg concentration, a middle-gap trap with the activation energy of 1870 meV was found to be predominant. The results are confirmed and quantitatively described by temperature-dependent Hall effect measurements. The mechanism of nitrogen atom displacement due to the local strain field arising in SI AT GaN:Mg is proposed and the effect of the Mg concentration on the charge compensation is discussed.