Preparation of the atomically straight step-edge Si (111) substrates as templates for nanostructure formation

摘要

We report on the experimental discovery that the distribution of kinks along steps on vicinal Si(111) surfaces depends on the direction of the dc current passed along the steps for resistive annealing. The as-cleaned Si(111) surface miscut ～1° towards [112] has a small ( < 3°) unavoidable azimuthal deviation, which produces a number of kinks along the step-edges. When the azimuthal misorientation is from [112] towards [110] ([110]), dc current flowing in the direction [110] ([110]) climbing up the kinks straightens the step-edges as opposed to the current flowing in the opposite [110] ([110]) direction. During annealing around 800℃, the dc current in the direction climbing up the kinks straightens the steps. The up-climbing current direction transports and concentrates the kinks in a region outside the template area, leaving a kink-free atomic step-edge region as an ideal template for a variety of nanostructure formations. The straight step edges produced in this manner have uniform atomic configuration known as U(2, 0).