Effect of modification of S-terminated Ge(1 0 0) surface on ALD HfO2 gate stack

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 O3-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.