Experimental and theoretical evidence is presented for the metastability of oxygen donors in AlxGa12xN. As the aluminum content increases, Hall effect measurements reveal an increase in the electron activation energy, consistent with the emergence of a deep DX level from the conduction band. Persistent photoconductivity is observed in Al0.39Ga0.61N:O at temperatures below 150 K after exposure t...

It is demonstrated that a wing of the Hofstadter diagram calculated for the tightly-bound s-electrons in the simple cubic lattice can be reproduced by the dispersion figure of the wave-vector square considered for the electron states of the same lattice, on the condition that the states having equal energies are taken into account. The dispersion splitting increases systematically with the dist...

The paper continues the rigorous investigations of the mean field Green function solution of the effective two-dimensional two-band Hubbard model [N.M. Plakida et al., Phys. Rev. B, 51, 16599 (1995)] of the superconducting phase transitions in cuprates, started in [Gh. Adam, S. Adam, J.Phys.A: Math. Theor., 40, 11205 (2007)]. Discussion of the (δ, T ) phase diagram of the model points to the di...

Single-, two-, and three-photon transitions were driven amongst five quantum states of a niobium persistent-current qubit. A multi-level energy-band diagram was extracted using microwave spectroscopy, and avoided crossings were directly measured between the third and fourth excited states. The energy relaxation times between states connected by single-photon and multi-photon transitions were ap...

author’s e-mail: [email protected] The extreme ultraviolet light source (EUVL) is being studied intensively toward its application in semiconductor technology [1]. Use of Mo/Si multilayer optics requires that the EUVL should produce emission at the 13.5 nm band with high efficiency (> 1%). Xe plasma has been considered as promising candidate, however, strong emission is usually obtained in...

We study the focusing properties of a two dimensional complex square-lattice photonic crystal (PC) comprising air holes immersed in Ge medium. The finite difference time domain (FDTD) method is utilized to calculate the dispersion band diagram and to simulate the image formation incorporating the perfectly matched layer (PML) boundary condition. In contrast to the common square PCs with the sam...

Graphene quantum dots are known to exhibit tunable photoluminescence (PL) through manipulation of edge functionality under various synthesis conditions. Here, we report observation of excitation dependent anomalous m-n type fingerprint PL transition in synthesized amino functionalized graphene quantum dots (5-7 nm). The effect of band-to-band π*-π and interstate to band n-π induced transitions ...

in this article, we suggested a novel design of polarization splitter based on coupler waveguide on inp substrate at 1.55mm wavelength. photonic crystal structure is consisted of two dimensional (2d) air holes embedded in inp/ingaasp material with an effective refractive index of 3.2634 which is arranged in a hexagonal lattice. the photonic band gap (pbg) of this structure is determined using t...