Analysis of microstructure and electrical properties of Al-doped p-type ZnO thin films

We present the Al-doped p-type ZnO thin films fabricated by RF magnetron sputtering on n-Si (100) and homo-buffer layers in pure oxygen ambient. Al₂O₃ 2wt%-mixed ZnO ceramic was selected as a sputtering target. XRD spectra show that the Al-doped ZnO thin films have ZnO crystal structure. Hall Effect experiments show that p-type carrier concentrations are arranged from 1.66times10¹⁶ to 4.04times10¹⁸ cm^-3, mobility from 0.194 to 198 cm² V^-1 s^-1 and resistivity from 0.0963 to 18.4 Omegacm. FESEM cross-sectional images show compact structure of a p- type ZnO:Al thin film annealed at 800degC with mass density of 5.40 g/cm³ which is smaller than that of theoretical value of 5.67 g/cm³.I-V curve of p-n junction shows rectifying feature with turn-on voltage of 1.8 V.