Atomically flat HfO2 layer fabricated by mild oxidation HfS2 with controlled number of layers.

In this work, homogeneous surface oxidation of hafnium disulfide (HfS₂) is achieved by an extremely simple thermal treatment, i.e., mild oxidization in air. Due to the high thermal stability of hafnium dioxide (HfO₂), atomically flat HfO₂ is formed on top of unoxidized HfS₂ and unlimited layer-by-layer oxidation is observed. The thickness of HfO₂ can be controlled by oxidation temperature and time. The HfO₂ layer fabricated by the oxidation of HfS₂ is smooth and atomically flat with roughness comparable to that of pristine HfS₂. Growth of a high-quality, uniform, atomically flat oxide film on top of semiconductor is the first step for the fabrication of field effect transistors and metal-insulator-semiconductor devices. Thus, our results will facilitate the future fabrication of HfO₂ films with atomic-scale thickness. [ABSTRACT FROM AUTHOR]