Al-doped p-type ZnO films were fabricated on n-Si (100) and homo-buffer layers in pure oxygen at $450^{circ}C$ of by RF magnetron sputtering. Target was ZnO ceramic mixed with 2 wt% $Al_2O_3$. XRD spectra show that the Al-doped ZnO thin films have ZnO crystal structure and homo-buffer layers are beneficial to Al-doped ZnO films to grow along c-axis. Hall Effect experiments with Van der Pauw configuration show that p-type carrier concentrations are ranged from $1.66{ imes}10^{16}$ to $4.04{ imes}10^{18};cm^{-3}$, mobilities from 0.194 to $2.3;cm^2V^{-1}s^{-1}$ and resistivities from 7.97 to $18.4;{Omega}cm$. p-type sample has density of $5.40;cm^{-3}$ which is smaller than theoretically calculated value of $5.67;cm^{-3}$. XPS spectra show that Ols has O-O and Zn-O structures and Al2p has only Al-O structure. P-ZnO:Al/n-ZnO:Al junctions were fabricated by magnetron sputtering. V-I curves show that the p-n junctions have rectifying characteristics.