S.B. Orlinskii

EPR identification of the triplet ground state and photoinduced population inversion for a Si-C divacancy in silicon carbide

It is shown that intrinsic defects responsible for the semi-insulating properties of SiC represent Si-C divacancies in a neutral state (VSi-VC)0, which have the triplet ground state. The energy level scheme and the mechanism of creating the photoinduced population inversion of the triplet sublevels of the divacancy ground state are determined. It is concluded that there is a singlet excited state through which spin polarization is accomplished, and this fact opens the possibility of detecting magnetic resonance on single divacancies.

Optically Addressable Silicon Vacancy-Related Spin Centers in Rhombic Silicon Carbide with High Breakdown Characteristics and ENDOR Evidence of Their Structure.

We discovered a family of uniaxially oriented silicon vacancy-related centers with S=3/2 in a rhombic 15R-SiC crystalline matrix. We demonstrate that these centers exhibit unique characteristics such as optical spin alignment up to the temperatures of 250°C. Thus, the range of robust optically addressable vacancy-related spin centers is extended to the wide class of rhombic SiC polytypes. To use these centers for quantum applications it is essential to know their structure. Using high frequency electron nuclear double resonance, we show that the centers are formed by negatively charged silicon vacancies V_{Si}^{-} in the paramagnetic state with S=3/2 that is noncovalently bonded to the neutral carbon vacancy V_{C}^{0} in the nonparamagnetic state, located on the adjacent site along the SiC symmetry c axis.

Giant change in the intensity of tunneling afterglow in excited ZnO quantum dots induced by the spin reorientation of electron-hole pairs in static and microwave magnetic fields

Long afterglow has been detected in light-excited ZnO quantum dots caused by the spin-dependent tunneling recombination of electron and hole centers. A giant increase in the intensity of afterglow upon a change in the spin orientation of electron and hole centers has been observed under electron paramagnetic resonance conditions, which allowed these centers to be identified.

Neutral and negatively charged silicon vacancies in neutron irradiated SiC: a high-field electron paramagnetic resonance study

High-field pulsed and continuous-wave electron paramagnetic resonance (EPR) techniques at 95 GHz have been used to investigate radiation defects in neutron-irradiated SiC. In the temperature range between 1.2 and 300 K three types of EPR spectra were observed in 4H-and 6H-SiC crystals that are attributed to the neutral silicon vacancy, the negatively charged silicon vacancy, and the carbon vacancy. In the EPR spectra of V - Si in 4H- and 6H-SiC an anisotropic splitting of the EPR lines is observed. This splitting is assumed to arise from small differences in the g-tensor of the quasi-cubic (k) and hexagonal (h) sites. The g-factor for the k site g (k) is found to be isotropic with g(k) = 2.0032 and the g-factor of the h-site is found to be slightly anisotropic with g λ (h) is = g(k) - 0.00004 and g⊥(h) = g(k) - 0.00002. The 95 GHz EPR spectra at 1.4 K show that the ground state of V u Si , is a triplet state. Additional 9.5 GHz EPR experiments reveal signals that are attributed to the carbon vacancy on the basis of the observed hyperfine splitting. The results demonstrate that V - Si , V 0 Si and V c are dominant defects after neutron irradiation of SiC to doses up to 10 19 cm -2 .

Electron Paramagnetic Resonance Based Spectroscopic Techniques

This chapter addresses the use of electron paramagnetic resonance based spectroscopic techniques to study nanostructures. Particular attention is given to high frequency electron spin echo, electron-nuclear double resonance and optically detected magnetic resonance spectroscopy.