Browsing by Subject "Conduction band"

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Open Access
Dynamics of sliding and loading bilayer graphene
(2022-09) Edun, Benjamin
Sliding and loading bilayer graphene is investigated using the Tight Binding method. We develop interaction-distance dependent tight binding parameter functions to allow for the calculation of band structure for different interacting distances. We investigate the band structures of sliding graphene and loading bilayer graphene, in which case the latter consists of varying interlayer distances between monolayers. We show that based on developed parameter models, band splittings can be seen to emerge in the band structures, which follow different patterns for different sliding directions. As expected we con rm that for varying vertical interlayer distances, monolayer graphene band structure is the limit for both AA and AB stacking con gurations. By applying a quadratic energy model to the curvature of the band structures in the vicinity of the K-point for AB stacking con guration we predict the effective mass of electrons and holes in bilayer graphene, and electrons in monolayer graphene. We also show the pattern of change of effective mass with respect to changing interlayer distance, and try to investigate where our prescribed quadractic energy model breaks down, as we approach the limit of the monolayer band structure.
Open Access
Temperature-and excitation intensity-dependent photoluminescence in TlInSeS single crystals
(American Institute of Physics, 2002) Gasanly, N. M.; Aydınlı, Atilla; Yuksek, N. S.
Photoluminescence (PL) spectra of TlInSeS layered single crystals were investigated in the wavelength region 460-800 nm and in the temperature range 10-65 K. We observed one wide PL band centred at 584 nm (2.122 eV) at T = 10 K and an excitation intensity of 7.5 W cm-2. We have also studied the variation of the PL intensity versus excitation laser intensity in the range from 0.023 to 7.5 W cm-2. The red shift of this band with increasing temperature and blue shift with increasing laser excitation intensity was observed. The PL was found to be due to radiative transitions from the moderately deep donor level located at 0.243 eV below the bottom of the conduction band to the shallow acceptor level at 0.023 eV located above the top of the valence band. The proposed energy-level diagram permits us to interpret the recombination processes in TlInSeS layered single crystals.