First Principle Investigation Of Doped SiC and ZnO For Optoelectronic Applications

Abstract

Abstract newlineThis dissertation provides a comprehensive examination of pristine and doped silicon carbide newline(SiC), and zinc oxide (ZnO) systems, utilizing a first-principles density functional theory newline(DFT) methodology to explore their structural, electronic, magnetic optical properties for newlineoptoelectronic devices. Zigzag SiC Nanotubes ((8,0), (9,0), (10,0)) were systematically studied newlinetogether with ZnO primitive and supercell models utilizing BIOVIA Materials Studio with the newlineCASTEP module in the intrinsic, transition metal doped and group-III doped configuration newlineincluding oxygen vacancies for ZnO. newlineIntrinsic SiC nanotubes possessed well-defined semiconducting behavior, with their band gap newlinenarrowing as the diameter increased owing to quantum size effects. Their optical behavior newlineexhibited high absorption in the UV and low absorption in the visible, indicating their newlinetransparency. Doping with transition metals vanadium and manganese exhibited large newlineelectronic and magnetic changes. V-doped SiC nanotubes exhibited half-metallicity with high newlinespin polarization and would therefore be suitable for spintronic devices and UV photodetectors. newlineMn-doped SiC nanotubes exhibited half-metallic magnetic semiconductor behavior under UV newlinelight, with extended absorption into the IR range, and could be promising materials in IR/NIR newlinesensors applications. newlineIn the case of ZnO systems, confirmed that intrinsic ZnO is a wide band gap semiconductor newlinewith lattice parameter values comparable to what was determined experimentally. Doping with newlineGroup-III elements (B, Al, Ga, In) led to a significant increase in n-type conductivity; the newlineatomic radius of B, Al, and Ga, which is smaller than the radius of Zn, led to decreases in the newlinelattice constants while the doping of In cause expansion in the lattice constants of ZnO. newlineOxygen vacancies were crucial because they introduce shallow donor states near the energy of newlinethe conduction band edge, which increased carrier concentrations in the samples and altered newlinethe optical responses of samples