Homogeneous hydrogen-terminated Si(111) surface formed using aqueous HF solution and water

Aqueous HF etching of silicon surface removes surface oxide, leaving a silicon surface terminated by atomic hydrogen. We studied the effect of the immersion in water, following HF etching, on the surface hydride structure and flatness, by measuring Si-H stretching vibration using infrared absorption spectroscopy. Immersion at 20 °C flattens the Si(111) surface, which is atomically rough just after etching, to some extent. Boiling water (100 °C) produces an atomically flat surface homogeneously covered with silicon monohydride (—SiH) normal to the surface and free of oxidation. The surface has a low defect density of less than 0.5%.