Ferroelectric complex perovskites, such as lead zirconate titanate (PZT), strontium bismuth tantalate (SBT), and lead magnesium niobate-lead titanate (PMN-PT) have been widely used in ferroelectric devices. However, these traditional ferroelectric materials have a limitation in thickness scaling and are incompatible with CMOS processes. In the last few years, doped metal oxides, including hafnium oxide (Hf02) and zirconium oxide (ZrO2), were found to have ferroelectric phase -. Ferroelectric HfO2 has the advantages of a high coercive field, excellent scalability (down to 2.5nm), and good compatibility with CMOS processing -. In this paper, we systematically investigate Al-doped HfO2 with various electrodes, Al compositions and annealing temperatures. We found that Ti/Pd is a promising candidate as top electrode material for ferroelectric HfO2.