When S-termination on a Ge(1 0 0) surface was desorbed at an elevated temperature and an atomic layer deposition (ALD) HfO2 film was deposited, interfacial thickness was less than 1 nm. As a result, the equivalent oxide thickness (EOT) of the stack on the initially S-terminated surface was thinner than that deposited on the O-3-oxidized surface, while HfO2 film thickness was almost identical on both surfaces. Nevertheless, the HfO2 stack on the initially S-terminated surface exhibited improved leakage current characteristics due to an increase in barrier height. Its thinner but robust interface will contribute to the scaling down of gate oxide integrity. (C) 2009 Elsevier B. V. All rights reserved.