A method of preparing a semiconductor work surface comprises the steps of forming an Si monocrystaline substrate including a semiconductor work surface, removing by wet-etching a silicon oxide film formed on the work surface, using HF solution, and washing the work surface by pure water, serving as a washing liquid, of a dissolved oxygen concentration of 500 ppb or lower. The work surface is made of monocrystal and has an orientation a certain amount off the (001) plane. The certain amount is set such that an axis of the work surface has a component inclined with an angle of from 1.degree. to 5.degree. from the [001] direction to a direction. The washing liquid of pure water has a property of etching the Si monocrystal, such that a single or a plurality of surfaces, including the (111) plane, can be preferentially exposed.