Metal-oxide-semiconductor capacitors with HfAlO high-k gate dielectric deposited by Atomic Layer Deposition (ALD) and SiGe channel were studied in this work. A thin Si layer was also grown upon SiGe channel layer as a capping layer to form a Si/SiGe/Si structure on substrate. Different Ge contents from 7% to 32% in SiGe channel on electrical characteristics of MOS device were investigated. Based on gate leakage and reliability properties of MOS devices, the optimal Ge content in SiGe channel to achieve enough mobility enhancement is around 20%. The improvement of electrical characteristics includes low leakage current, small EOT value and good reliability. (C) 2009 Elsevier Ltd. All rights reserved.