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

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

Bariloche

Simposio; XXIII Latin American Symposium on Solid State Physics; 2018

Band-edge photoluminescence of zinc oxide (ZnO) materials reveals a phonon-assisted ultraviolet emission enhanced by Na doping. Wereport synthesis of pure and Na doped ZnO, and changes in structure and optical properties as a function of doping concentration andsynthesis temperature. The obtained samples are nanoneedles, microparticles, and microwires. Room temperature photoluminescencereveals a contribution of band bending at the surface of the nanostructures, decreasing with Na concentration. Franz-Keldysh effectpredicts strong electric field localized in the depletion region and appears to be the cause of red-shift in UV band emission of nanoneedlesin comparison to microwires. Our results indicate that Na doping introduces an acceptor level between 150 and 200 meV above thevalence band. Na doped ZnO microwires are promising semiconductor structures for room-temperature blue/UV optoelectronics.