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Abstract Title: Center and Use Bold, 14-Point Times Roman Type, Capitalizing Only the First Word

Ordered GeSi quantum rings grown on patterned Si (001) substrates

Jian Cui,Yingjie Ma,Yongliang Fan, Zuimin Jiang, Zhenyang Zhong*

Surface Physics Laboratory (National Key Laboratory), and Department of Physics, Fudan University, Shanghai 200433, China

Ordered silicon-based nanostructures have attracted considerable attentions due to their unique properties and potential applications in various novel devices including field-emission displays, nanoelectronic and nanophotonic devices[1,2].It is convenient to use nanosphere lithography (NSL) technology to fabricate periodic patterns for it is cheap but effective. NSL has been used to fabricate periodic SiGe quantum dots (QDs) with the period down to 100 nm. [3] Self-assembled quantum ring (QR) is a kind of newly discovered nanostructures. [4] The special topological configuration has shown interesting quantum effects, e. g. persistent current in normal metal rings. [5] In this report, we will present highly ordered GeSi QRsin large areasgrown on patterned Si(001) substratesby molecularbeam epitaxial.

The inverted pyramid-like pitsarranged in a hexagonal lattice on Si(001) substrates were fabricated by reactive iron etching(RIE) and NSL technology [6]. The main fabrication processes of the patternwereshown in Fig. 1. After the hexagonal PS pattern was formed (Fig. 1 (a)), the pattern was etched by RIE to shrink the coverage of PS (Fig. 1 (b)). This step is necessary to the subsequent formation of QRs, because the large distance between QDs ensures the independent development of QRs when capping. The ordered inverted pyramid-like pits were obtained by selective etching of Si in KOH solution. The ordered GeSi QRs werethen grown via a two-step process. First, ordered domeshaped GeSi QDswere grownon the patterned substrates at610 °C,as shown in Fig. 2 (a). Second, a thin Si capping layer was deposited at 610°C. By controlling the amount of deposited Si, the GeSi QDstransform into GeSi QRs[4].


Then highly ordered GeSi QRs arrays were formed, as shown in Fig. 2 (b). The period of rings was pre-determined by the pattern on Si substrates, which can be readily modulated by using PS nanospheres in different sizes. The size of rings was closely associated with the size of capped GeSi QDs and the Si capping process.Parameters including the size of PS nanospheres, RIE processing parameters, growth temperature and thickness can be adjusted and optimized to control the size and periods of QRs.These ordered GeSi QRs may have unique properties.

*

[1]V. V. Poborchii,et al., Appl. Phys. Lett. 75, 3276 (1999).

[2]L.J. Heyderman, et al., Appl. Phys. Lett. 85, 4989(2004).

[3]P. X. Chen, et al., Nanotechnology. 20, 095303 (2009).

[4]J. Cui, et al., Appl. Phys. Lett. 83, 2079 (2003).

[5]H. Bluhm, et al., Phys. Rev. Lett. 102,136802 (2009).

[6]H. W. Deckman,et al.,Appl. Phys. Lett. 41, 377 (1982).