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The properties of the substitutional impurities of the second period of the periodic table incorporated into graphene were investigated. The Green's-functions framework and the tightbinding method without the effect of the lattice distortion were used. We discuss the possibility of the existence of well-defined resonant states in the valence band or the conduction band in the vicinity of the Dirac point. We conclude that in the vicinity of the Dirac point there was a possibility of a coincidence of the Fermi energy levels with impurity resonances (i.e., the Fermi level is pinned to the impurity resonance level.) ß

Deep hole traps in p-type Al0.5Ga0.5As grown by molecular beam epitaxy have been studied by the deep-level transient-spectroscopy method applied to samples with a Schottky diode configuration. Five hole traps, labeled as H0 to H4, were found. For traps H1, H3, and H4 the activation energies for emission were ET1=0.14 eV, ET3=0.40 eV, and ET4=0.46 eV, respectively. Hole emission from trap H2 was dependent on the external electric field. The emission rate obeyed the Poole–Frenkel relation. When extrapolated to zero electric field, the thermal activation energy for hole emission was ET2,0=0.37 eV. Capture cross sections for traps H1 and H4 were thermally activated with energy barriers EB1=0.04 eV and EB4=0.18 eV, respectively.

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BYIn multi-component mixed semiconducting c r y s t a l s treated in the virtual-crystal approximation /I/, the additional mechanism of c a r r i e r scattering appears due t o chemical disorder of component atoms. Disorder scattering was in-