Advances in Control of Nano and Micro Structure of Na Doped ZnO. Effect of Doping on Excitons and Phonon-Assisted UV Emission

STRAUBE B; SIMONELLI G; RODRIGUEZ TORRES C.; FERREYRA J. M.; VILLAFUERTE M; PEREZ DE HELUANI S.; BRIDOUX G; ZAPATA C.; ESQUINAZI P.

San Carlos de Bariloche

Congreso; 21. SLAFES XXIII; 2018

Instituto Balseiro

Band-edge photoluminescence of zinc oxide materials reveals a phononassistedultraviolet emission enhanced by Na doping. We report thesynthesis of ZnO and Na-doped ZnO, the changes in structure and opticalproperties as a function of doping concentration and synthesis temperature.The obtained samples are nanoneedles, microparticles, and microwires. Thestructural effect of Na doping is studied by X-ray diffraction and Ramanspectroscopy. Room temperature photoluminescence reveals a contributionof band bending at the surface of the nanostructures, decreasing with Naconcentration. Franz?Keldysh effect predicts strong electric field localized inthe depletion region and appears to be the cause of red-shift in UV bandemission of nanoneedles in comparison to microwires. Our results indicatethat Na doping introduces an acceptor level between 150 and 200meVabove the valence band.