Effect of Co-doped Concentration on Microstructure and Photoelectric Properties of Na-Al Co-doped ZnO Thin Films

Abstract

Sodium and aluminum (Na-Al) co-doped ZnO thin films (NAZO) were prepared on the quartz glass substrate by sol-gel spin-coating method. The effect of different Na-Al co-doped concentration on crystallization, microstructure and photoelectric properties of ZnO films were investigated. The results show that all NAZO thin films samples grow along the c-axis of the preferred orientation; appropriate Na-Al co-doped concentration can improve the ZnO films crystallization, increase the carrier mobility; meanwhile, six columnar grain structure crystal particles can be observed on the NAZO films surface. With the changing of Na-Al co-doped concentration, the highest mean optical transmittance reaches 95%. Because of the difference of the solid solution ratio, the appropriate concentration can improve the efficiency of doping Na-Al element, which enhances the carrier concentration of the film inside and the resistivity decreases; the lowest resistivity of NAZO thin films is 4.7×10-2Ω·cm.

Keywords

• ZnO
• sol-gel
• Na-Al co-doped
• microstructure
• optical property