Influence of Doping and Co-doping on the Behavior of Sputtered ZnO Thin Films

摘要

A co-dopand approach was used to investigate influence of gallium-nitrogen co-doping on the microstructure and electrical parameters of ZnO. ZnO:Ga:N thin films were deposited by rf diode sputtering at varying nitrogen content (0÷100%) in Ar/N_2 gas. ZnO:Ga films (0% N_2) showed minimum resistivity of 0.12 Ωcm, electron concentration of 2.5×10~(19) cm~(-3) and mobility of 2 cm~2/Vs. A hole concentration of 2.6×10~(18) cm~(-3), a mobility of 2 cm~2/Vs and a resistivity of 1.5 Ωcm in ZnO:Ga:N resulted from the deposition with 100% N_2 in Ar/N_2 gas. XRD patterns revealed a profound impact of Ga-N co-doping on film orientation. The estimated crystallite size varied from 234 to 41 nm, depending on the N_2 content. TEM images of the co-doped films along with the corresponding selected area diffraction pattern indicated a polycrystalline, columnar layer with a c-axis preferred orientation. AFM images demonstrated the different crystalline structure and grain formation depending on nitrogen content.