Morphology change and its chemical states at the Si(1Â 0Â 0) surface after dipping in hot ultrapure water

The changes in morphology and chemical states of Si(1 0 0) surface upon dipping in ultrapure water were investigated by using X-ray photoelectron spectroscopy and atomic force microscope. In ultrapure water, the oxidation and the etching competitively progressed at the Si(1 0 0) surface after HF treatment and made the smooth surface rough. However, the surface covered with a thick native oxide film was not etched at all. That meant the precise Si4+ component remained without being etched, whereas rest parts of the surface could be etched. This selective etching led to the rough surface morphology. O− and OH− ions might take oxidizing and etching at the surface after HF treatment.