Optical dynamics at Se/CdBr, interfaces رسالة ماجستير

Abstract

In the current work, we designed and characterized a new class of optical receivers. The optical interfaces are fabricated by the physical vapor deposition of CdBrz onto selenium substrates. The compositional, optical and dielectric properties of the Se/CdBr, films are investigated in details. It is observed that thin films of selenium exhibit structural transitions from amorphous to polycrystalline phases after four weeks of deposition. The formed hexagonal phase of selenium strongly interacted with the hexagonal CdBr, forming novel characteristics. From structure point of view, coating of CdBr2 onto Se decreases the defect density of Se, increase the crystallite sizes and lowered the percentage of stacking faults. Optically, Urbech’s band tails are formed, free carrier absorption is enhanced, the energy band gap of selenium shrinks. The formation of Se/CdBrz interfaces is accompanied by the conduction and valence band offsets 1.25 eV and 0.63 eV, respectively. On the other hand, the dielectric dispersion analyses have shown that the formation of Se/CdBrz results in resonant dielectric spectra. The real part of the dielectric spectra of Se, CdBrz and Se/CdBr2 have shown the possible formation of two dielectric resonators centered in the visible and near infrared ranges of light. The study here additionally included the optimization of the optical conductivity parameters for Se/CdBr, optical receivers. It was observed that the interfaces exhibit more efficient drift mobility with a Plasmon frequency that suits 4G/SG communication technology. We believe that optical interfaces can perform well in

the optical communication technology.