Regular step arrays on silicon

Abstract

Highly regular arrays of steps are produced on vicinal Si͑111͒7ϫ7. The step edges are atomically straight for up to 2ϫ10 4 lattice sites. The terraces are single domain, which produces a minimum kink width of 2.3 nm ͑half a 7ϫ7 unit cell͒ and thus a high barrier for creating kinks. Criteria for obtaining optimum step arrays are established, such as the miscut ͓Ϸ1°towards ͑112͔͒ and an annealing sequence which passes through step bunching regions quickly.

Chains of gold atoms with tailored electronic states

“…Stepped Si͑111͒ templates have been prepared with high perfection by appropriate annealing sequences. [29][30][31] At low enough coverage there is only a single gold chain in the unit cell of such vicinal surfaces, while the flat Si(111)5 ϫ2-Au structure consists of two Au chains per unit cell. 32 Figure 1 shows how vicinal Si͑111͒ surfaces containing the stable ͓1 1 0͔ steps can be classified into two groups, one tilted with its normal towards the ͓1 1 2 ͔ azimuth with one broken bond at the step edge, the other towards ͓1 1 2͔ with two broken bonds.…”

“…Interestingly, the Si(111)5ϫ2-Au surface appears to be stabilized by a lattice gas of additional Si atoms that provide the energetically optimal band filling. 31,38 Thus autodoping by built-in defects might be a common phenomenon in these chain structures.…”

“…First, clean silicon surfaces are prepared using a previously optimized heating sequence 31 that produces straight, regularly spaced steps on vicinal silicon wafers. Next, the appropriate gold coverage ͑see Table I͒ is deposited with the surface at an elevated temperature of 650°C.…”

Self-assembly of periodic nanoclusters of Si and Ge along atomically straight steps of a vicinal Si(111)

“…16 Himpsel and co-workers have experimentally demonstrated that vicinal Si͑111͒ surfaces can serve as templates for self-assembly of one-dimensional ͑1D͒ nanostructures, 17,18 because a regular array of straight steps can be obtained on these surfaces. [19][20][21] Improving their method of the straight-step preparation by substrate annealing with step-parallel direct current ͑dc͒, we have found that the "kink-up" direction ͑ascending kinks of the steps͒ of the dc is effective to obtain atomically straight step edges ͑on the order of 1 m in length͒ probably due to electromigration of the surface atoms. 22 We have studied the growth behavior of Si ͑Ref.…”

One-dimensional ordering of Ge nanoclusters along atomically straight steps of Si(111)

“…14,15 On the other hand, self-assembly of one-dimensional ͑1D͒ nanostructures such as of Au and CaF 2 has been demonstrated 16,17 by using regular step arrays on vicinal Si͑111͒ surfaces. [18][19][20] In this letter, we study self-assembly of Ge on such highly ordered step substrate of Si͑111͒-7 ϫ 7. Scanning tunneling microscopy ͑STM͒ reveals the growth mechanism of 1D arrays of Ge nanoclusters along the step edges.…”