L. S. Vlasenko

Optical detection of magnetic resonance and electron paramagnetic resonance study of the oxygen vacancy and lead donors in ZnO

Optical detection of magnetic resonance (ODMR) and electron paramagnetic resonance (EPR) spectra are investigated in ZnO single crystals. The strong negative ODMR line with axial symmetry of the g-tensor around the c axis with g∥=2.0133±0.0001 and g⊥=2.0135±0.0001 is ascribed to Pb3+ ions. The strongest Pb3+ ODMR spectrum is observed under excitation with visible light from an Ar+ ion laser and below 40Hz of on/off microwave power modulation. The negative Pb3+ line, accompanied with effective mass (EM) donors over the spectral range of the photoluminescence (PL), shows spin dependent transfer of electrons from EM donors to Pb3+, competing with PL. The intensity of the Pb3+ EPR line as well as the EPR line of oxygen vacancy (VO+) investigated in samples irradiated with 2.5MeV electrons show a fast increase when the light is switched on and gradual decrease during illumination. The dependence of the growth and decay kinetics of the Pb3+ and VO+ EPR spectra on wavelength of light is analyzed by taking into a...

Persistent photoconductivity and electron paramagnetic resonance in zinc oxide ceramics

The effect of persistent photoconductivity is observed in zinc oxide (ZnO) ceramics together with persistence of the electron paramagnetic resonance (EPR) spectra of defects and impurity centers in the samples. The spectral and time dependences of the EPR signals and microwave photoconductivity are investigated under excitation by light with different quantum energies below the ZnO band gap. The mechanisms of the persistent photoconductivity and coexistence of pnotoconductivity and optically induced EPR spectra after switching off the light are discussed. Based on the experimental results it is concluded that surface and intergranular conductivities dominate in ZnO ceramics.

Preparation of one to three unit cell thick powders and investigation of their magnetic and microwave properties

Nanocrystalline powders have been prepared by a citrate gel modification of the sol - gel technique. Using a relatively low temperature, , and (i) a process of extracting oxygen and reoxidizing the precursor powder or (ii) a sequence of vacuum annealing and prolonged heating in air, it was possible to avoid sintering of the particles. According to x-ray powder diffraction analysis the particles have orthorhombic structure pertinent to the phase. Measurements made by atomic force microscopy show that they have flat shape with two maxima in the thickness distribution, one at 1.2 nm and the other at 3.8 nm , corresponding to one or three orthorhombic unit cell lengths of the crystal. The average width of the particles is 40 nm. A similar value could be obtained from XRD measurements and the width of microwave absorption line around zero applied field. Superconducting properties of the powders were investigated with magnetization measurements.

Electrical detection and magnetic-field control of spin states in phosphorus-doped silicon

Electron paramagnetic resonance of ensembles of phosphorus donors in silicon has been detected electrically with externally applied magnetic fields lower than 200 G. Because the spin Hamiltonian was dominated by the contact hyperfine term rather than by the Zeeman terms at such low magnetic fields, superposition states

Coherent storage of photoexcited triplet states using 29Si nuclear spins in silicon.

\alpha{}| \uparrow \downarrow >+\beta{}| \downarrow \uparrow >

Identification of a paramagnetic recombination center in silicon/silicon-dioxide interface

and

Electron paramagnetic resonance of radiation defects in hydrogen-implanted silicon detected by spin-dependent microwave photoconductivity

-\beta{}| \uparrow \downarrow > + \alpha{}| \downarrow \uparrow >

Linewidth of low-field electrically detected magnetic resonance of phosphorus in isotopically controlled silicon

were formed between phosphorus electron and nuclear spins, and electron paramagnetic resonance transitions between these superposition states and

Spin-dependent recombination electron paramagnetic resonance spectroscopy of defects in irradiated silicon detectors

| \uparrow \uparrow >

Photoelectrically detected magnetic resonance spectroscopy of the excited triplet states of point defects in silicon

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